When do you start flying runway heading?
Posted by Mike__O@reddit | flying | View on Reddit | 147 comments
I've been flying for a long time and still trying to learn things. This particular question came up during a sim I had recently. It was never debriefed because I met the evaluation standards and I didn't want to open any cans of worms.
So say you're taking off with a fairly strong crosswind. Your departure instructions are "fly runway heading, climb and maintain 5000"
We all [should] know that assigned headings are where they want you to point the nose, and the pilot should not apply drift corrections to an assigned heading.
When taking off IFR with a strong crosswind, you will eventually need to remove your crosswind controls and allow the airplane to weathervane into the wind. Removing those crosswind controls and pointing the nose to runway heading will result in a downwind drift that will take you off the extended runway centerline.
So my question is when is it procedurally correct to transition from maintaining runway centerline to flying the assigned runway heading? In my sim I did it passing 400' AGL, but this resulted in me being a decent bit off runway centerline by the departure end.
What is the procedurally correct answer here?
y2khardtop1@reddit
Personally if I get a “maintain runway heading” I continue a reasonable correction as at my Delta it’s almost always traffic entering the pattern and I dont want to drift toward them. Now if it’s an IFR departure, they are just putting me in a safe space until I get handed over to departure, so after clearing pattern altitude I’ve lost the runway anyway.
Heel-Judder@reddit
Totally irrelevant and absolutely incorrect. You are not supposed to maintain wind correct. You are expected to fly a HEADING.
If they said "fly straight out" then you are expected to maintain the extended centerline.
y2khardtop1@reddit
Magnetic or runway number!
Heel-Judder@reddit
I'm sorry...what are you asking?
hawker1172@reddit
I will say there are some rouge class delta controllers that say runway heading and get mad when you drift off runway track. If you know you know.
zero_xmas_valentine@reddit
Yes. Those controllers are wrong.
I remember getting absolutely barked at by an approach control that normally didn't deal with small stuff because I wasn't on their headings. Like yeah man 50 knots of wind at 3000' will do that.
hawker1172@reddit
Yeah well not saying it’s right but get ready to have to defend yourself to the FSDO when they give you a number. Depends how willing you are to die on that hill if you operate out of an airport like that regularly.
NoGuidance8609@reddit
So you are “personally” choosing to not follow a specific ATC clearance? Might want to reconsider your personal choices and review phraseology and procedures.
Rictor_Scale@reddit
I only fly VFR right now, but I stay on the runway ground-track using wind-correction as I consider this a ground reference type instruction. I do the same with "extend downwind" etc. Any other time in towered airspace I fly the assigned heading and let the tower worry about wind adjustments.
BusterScruggs_SC@reddit
If they tell you to fly runway heading and you maintain runway ground track then you are not following ATC's instructions.
Rictor_Scale@reddit
Where I fly these VFR instructions are usually for just a mile or two and we are stuck under a shelf at 1000. But I just called local ATC and told them they were down-voted by Reddit and should start allowing departing planes to collide with incoming traffic on long downwinds packed with students flying the downwind ground track.
Kseries2497@reddit
You should tell those clowns to fix their phraseology instead. Or contact the FSDO if you don't want to throw down with them DCA-style.
Rictor_Scale@reddit
I appreciate you good manners and logical reply. That's getting rarer and rarer these days on Reddit and especially this forum.
Kseries2497@reddit
I'm joking, but only partially. If your tower is telling you "fly runway heading" but they don't mean "fly runway heading," they're doing it wrong. "Track the runway centerline" or "extend upwind leg" would be more appropriate here. The FSDO could fix them up, or you could go up and fist fight them.
Heel-Judder@reddit
This is not a question for VFR pilots.
Rictor_Scale@reddit
This isn't the /IFR_flying subbreddit. This is the /flying subreddit. This same instruction is regularly given to both types of pilots and has common ground considerations for both. I specifically prefaced my comment with the "VFR" application.
Heel-Judder@reddit
That was the entire premise of this discussion. You're out of your league here, buddy. Nice try, though.
mkosmo@reddit
You shouldn't do that. When they say "runway heading" they mean heading, not course. Words matter here.
Telling you to extend a leg is another subject entirely. Those aren't headings.
TinCupChallace@reddit
As a radar controller. I wouldn't notice or care. I'm giving you runway heading to avoid traffic/moa/etc that is in the direction of your on course heading. You are being separated by non radar until we get you on radar. Once I get you on radar, I'll reevaluate whatever my needs are and get you climbing/turned/etc. Due to winds, I have almost zero ability to give precise vectors based on headings and I work my sector based on that limitation. There isn't a world where I could violate you for being 3 degrees off from where I expected you to be. There also isn't a world where I would care to do the paperwork to violate you for just about anything.
wt1j@reddit
If you’re ARTCC sure, but if you’re tower I think what OP is asking is if they’re switching to runway heading at 400 AGL with a crosswind is that ok, or is there a potential issue with say parallel traffic flying runway course and colliding?
As pilots we all feel weird being told to fly runway heading with a crosswind because we know we’re drifting and we’re blindly trusting ATC to know that and take it into account. It’s a good question.
srbmfodder@reddit
We were laughing about one of the departure turns out of LGA saying "fly runway heading to '500, then turn to 040". The runway was 044 I believe. I'm sure it was some legacy/modified stuff that ended up turning into that, but we figured a 4 degree turn was not going to change anything. Of course we complied.
randombrain@reddit
As a tower controller it can absolutely make a difference and we are absolutely using radar separation right from the beginning, even before the #2 aircraft pops up on the scope—which is an allowable use of radar separation per 5–5–1b2.
If two aircraft are given the same heading the required separation between them is 3NM. But if the headings diverge by at least 15° then the minimum is just 1NM.
Most procedures I've seen call for at least 20° just to be safe... but if "Runway 27" is actually 275°, I'm legal to give the first guy a "turn left heading 260" and the second "fly runway heading." If the second pilot decides to just fly heading 270 that's a separation error. A difference of a few degrees can matter.
JDLovesTurk@reddit
He also wasn’t flying runway heading though. After being assigned fly runway heading, we look at the chart and dial in the number published. When we line up on the runway, we verify that the published number matches the DG. At 400’, we select and fly that heading.
randombrain@reddit
Right, he wasn't. I was specifically pushing back against /u/TinCupChallace saying "I wouldn't notice or care."
I believe TCC is a Center controller and probably doesn't work a lot of airports, if any, that run departures back-to-back with only 1NM separation. As a tower controller with automatic IFR releases, we do do that and we do care that you specifically fly runway heading rather than flying the number painted on the runway. (Notice, perhaps or perhaps not. Care, definitely. To keep us legal.)
Bunslow@reddit
the final parenthetical is amusing in that typical "ah what redtape nonsense" way
Kseries2497@reddit
Put it to you this way: If I'm separating you from another aircraft using minimum divergence, that's only 15°. If you eat up 30% of that by not flying runway heading like you were meant to do, it's going to look even closer than it already does.
Mispelled-This@reddit
3 degrees? For us little guys in strong winds, runway heading could give a track 30+ degrees off centerline. That’s extra fun when you’re being blown toward a parallel runway.
BeeDubba@reddit
Sometimes it's more than 3 degrees!
I took off runway 4 at Navy New Orleans KNBG with a right crosswind that increased to over 50kts by 500ft. I was climbing at 70kts (helicopter) and assigned runway heading, but quickly started drifting towards the towers north of the airfield, which I could no longer see because I was IMC. I asked the controller for a new heading due to the drift, but he insisted I continue to fly runway heading. I went ahead and turned away from them anyway and reported my new heading for "safety of flight" reasons.
I've lost track of the number of times military controllers have tried to kill me.
Mike__O@reddit (OP)
I always appreciate this kind of feedback from the other side of the scope.
MeatServo1@reddit
I agree the reg is that we don’t turn until 400 AGL, but “fly runway heading” isn’t a direction to begin a turn so much as to stay where you are (in that lateral plane). I looked in the instrument flying and instrument procedures handbooks (not that hard, admittedly), and it only mentions to not apply drift correction and to actually fly runway heading when instructed to do so as to prevent two planes drifting toward each other and losing separation during parallel runway operations.
At the extreme, if you flew runway heading as soon as the wheels left the ground, you might get close to the tower or other low, close-in obstacles. But at 400 feet, you’re well above anything on the airport surface.
I think holding centerline to 400 and then pushing the nose to runway heading is likely the right answer, but here’s a wrinkle. What do you do when taking off into low ceilings, either ILS or LPV mins or lower if you’re part 91 and feeling lucky, and can’t see the runway at 200 feet AGL and don’t have a navigator that will give you a dynamic wind correction angle? Just accept the albeit limited lateral drift between entering IMC and 400 feet?
Mike__O@reddit (OP)
Right, and that's where my knowledge base comes from as well. The issue is at relatively low speeds, wind drift can be somewhat significant. Using the "crosswind divided by ground speed" math means that a 15kt crosswind produces a 5 degree drift angle at 180kts, which is a reasonable average speed for an airliner in the initial takeoff phase of flight. 5 degrees is not an insignificant amount when you're talking about the immediate airport environment, especially with parallel runway ops.
Based on the replies so far, it seems the answer might not be entirely clear. 400A makes sense, but I might also have some negative transfer from my Air Force days. Air Force rules, and therefore what I taught in the T-1 was 400A AND past the departure end of the runway, if you could identify the departure end. The expectation was that you would make your best effort to remain over the runway for its entire length before starting any turns unless you were specifically instructed to do otherwise.
Heel-Judder@reddit
Pilot/Controller glossary -
AIM 5-2-9 e.1. -
Instrument Procedures Handbook Page 1-26 -
It couldn't be any more clear, I'm not sure where your confusion lies. You should not be tracking the runway centerline. They are expecting you fly a heading at 400 ft, just like everyone else. Everyone will be drifting with the wind. That's the point.
MeatServo1@reddit
Thanks for pulling out the AIM. I glanced at the IPH and IFH but didn’t think to consult that one. So then the answer is tracking runway centerline with wind correction angle, then turning to runway heading when 400 AGL and over the DER. That makes the most sense to me.
Heel-Judder@reddit
I disagree. The answer is to fly wings level at takeoff pitch until reaching 400 ft. That is what the flight director is commanding. That is what you are expected to fly. WINGS. LEVEL.
How are you going to track the runway centerline in 600 RVR? You don't. You fly WINGS. LEVEL. until selecting a roll mode at 400'.
XxVcVxX@reddit
I'm pretty sure Boeing/Airbus FD actually commands runway track, and not wings level on takeoff.
Heel-Judder@reddit
I have flown both, and am currently on a Boeing. They both command wings level until you request a roll mode.
JasonThree@reddit
At least on the 737 software we have, HDG SEL is active on selection of TOGA on the ground.
Heel-Judder@reddit
Is that the max?
JasonThree@reddit
Nope -800 NG
XxVcVxX@reddit
I'd read your FCOM again, unless you have a really old system, TO snapshots your track on rotation and commands it.
Heel-Judder@reddit
I went back and looked at our FCTM. And there is no track function after rotation. It says to minimize control wheel deflections to that which is required to keep the wings level.
XxVcVxX@reddit
I'm looking at my 767 and 737 FCOMs. Both state that the Flight Director TO mode maintains ground track on liftoff.
Oregon-Pilot@reddit
I can’t find anything in my airline’s 757/767 FM about what FD is commanding laterally when in TO mode. GA mode explicitly says it will command current track, but there’s nothing in my book about TO mode.
MeatServo1@reddit
The problem is not everyone has a flight director. So when I’m 200 AGL and enter the clouds, and I’m getting buffeted around so the yoke is dipping left and right, I’m just averaging wings level versus commanding some specific performance. Think back to your baby pilot days: how would you do this in a 172 or a Cherokee with no AP, no FD, and no glass?
Heel-Judder@reddit
You don't fly a transport category aircraft like you do a 172.
MeatServo1@reddit
Well, that’s a given. But OP didn’t ask about how to fly their 737 or his 172, just generally how do you fly this procedure. So wings level in a 121 environment / with a transport category aircraft is decided, but how about a commuter category like a king air (part 135 or part 91) and how about a normal category like a baron or a Mooney?
Heel-Judder@reddit
If I departed from a towered airport in a Baron, I would keep the wings level to maximize lift as much as possible during up to 400 ft, at which point I would fly the desired heading.
randombrain@reddit
I agree with you here. "Fly runway heading" isn't meant to be a "turn" as such, but if there's significant crosswind it can be. And if it is, then you begin the "turn" at 400 AGL just like any other turn you get assigned on takeoff.
MeatServo1@reddit
So in the absence of a FD, wings level or your best effort at it until 400 AGL, then “turning” back to runway heading, regardless of how far you are down the runway (aka irrespective of the departure end).
randombrain@reddit
I think you should probably wait until passing the DER; that's what TERPS is assuming, pass DER at or above 35' before commencing a turn. But unofficially I think that if you have the performance to make 400 AGL before the DER you're extremely unlikely to run in to any issues if you turn early. And from an ATC perspective it doesn't make a huge difference for us.
But to be clear, in my opinion the most correct option is to wait until you reach the DER, if that's something you can know.
nascent_aviator@reddit
When a diverse departure is authorized, TERPS provides obstacle clearance above 400 AGL even if you haven't passed the DER as long as you're at least 2000 feet down the runway.
Technically all bets are off if you turn before 2000 feet down the runway. But if you have the kind of performance to climb at a 1:5 slope I can't imagine there's anywhere you'd have a problem.
I'm not as clear on whether the same thing is true with published departure procedures.
MeatServo1@reddit
With some pilot math you can more or less figure it out, even in IMC, using DME distance to or from a navaid or using ground speed. I agree over or past the DER is the safest vis a vis TERPS. I’d love to see a more explicit, sourced answer, but between the IFH, IPH, AIM, P/CG, 121 pilots, 135 pilots, GA pilots, and ATC, this seems like a pretty well-formed answer.
Kev22994@reddit
Yeah, it’s pretty clear that you need to cross the departure end of the runway.
Mike__O@reddit (OP)
So 400' AGL, regardless of where you are in relation to the departure end of the runway? That's where I think some of the confusion (including my own) comes in. I grew up Air Force flying, and Air Force rules is you don't start any turns prior to 400' AGL AND past the departure end of the runway unless specifically directed otherwise. That means that pilots should make their best effort to remain over the runway for its entire length before starting any turns. I don't think any such rule exists in the FAA/civilian world, so I take it to mean that you begin your wind drift (by flying runway heading) at 400' AGL, no matter where you are relative to the DER.
Hopefully you can understand that it's not as cut-and-dry as you're attempting to claim it is.
Alfvenskus@reddit
A little clarification is needed. Obstacle clearance is assured by climbing at 200 feet per nautical mile starting at 35 feet above the DER. Then making the initial turn (away from RH) once you are 400 feet above DER. (Remember DER, TDZ, and ARP can all be different!)
Alfvenskus@reddit
The answer is in TERPS, for the US, and PANOPS elsewhere
Heel-Judder@reddit
It is as cut and dry as I'm factually representing it as.
You keep talking about the Air Force. This isn't the Air Force. This is the airlines. Stop talking about the Air Force. There's nothing worse than when a guy says "Well in the Air Force we did..."
There is no such requirement to wait until beyond DER to make a turn for a DVA, unless specifically stated. You are just making things up without having any factual basis for your claims. Meanwhile, I'm providing exactly what the rules, procedures, regulations, and company policies are.
For a Diverse Vector Area departure, you are in PITCH and ROLL mode at rotation (pitch is whatever normal for your fleet, say 20°). Roll is WINGS LEVEL. Your airplane will naturally weathervane into the wind during the rotation sequence. You climb WINGS LEVEL without regard for heading or track until 400', at which point you select heading regardless of your physical location. In a strong crosswind, you will be a few degrees off heading due to the aforementioned weathervaning.
End of story. It's not complicated. It's plain as day. You're not in the Air Force.
Mike__O@reddit (OP)
Something tells me you've got a great "I would have served but...." story
Heel-Judder@reddit
I would have served, but I didn't want to have to constantly talk about my BeechJet days in the Air Force.
MeatServo1@reddit
I would love someone to locate a definitive answer, because 400 AGL and past the DER makes sense to me, but clearly the community is all doing different things if we’re all nibbling around the edges in this thread. If you’re in a 172 in a 10 knot crosswind with a Vr of 55 knots and Vy of 70 knots, you’d be airborne in 1000 feet, it’d take a long time to reach the DER, and the better part of a minute to reach 400 AGL, so you’d be well off centerline before any of those points.
Looking at ground tracks online, it appears airliners are all dead nuts over the runway when they take off, but they’re only below 400 feet for maybe 12 seconds, not long enough for drift to really affect their path.
nascent_aviator@reddit
In a 20 knot crosswind, 12 seconds is a drift of 400 feet. Plenty to be noticeable.
Heel-Judder@reddit
I have yet to fly with a single pilot in corporate, freight, or airlines, who has not known to ask for heading select [runway heading or literally any heading] at 400 ft AGL for a Diverse Vector Area.
As for a definitive answer, it's published all over every regulation and in your company manual. My company publishes Departure Priorities. It says:
Plain as day. 400' is when you are authorized to turn. Anything below 400' and you are in pitch mode with wings level.
MeatServo1@reddit
It’s cute that you think every operation includes two crew and/or a functioning autopilot. Regardless, if you’d read earlier posts, you’d see no one disagrees that turns begin at 400 AGL. The disagreement is whether flying runway heading, as in flying a heading of 084° for runway 8 when there’s a 10 knot crosswind, should begin as soon as the wheels leave the ground or when you’re 400 AGL, and if the latter, is it track runway heading until 400 AGL, until crossing the DER, or until 400 AGL and crossing the DER. In the absence of FOM/GOM because either your company didn’t publish something specific about this or because you’re flying part 91, the difference matters.
Heel-Judder@reddit
You should not fly runway heading or track below 400 ft. You should be wings level, as the flight director is commanding on every transport category aircraft until you select a roll mode.
Heel-Judder@reddit
In a transport category aircraft, the flight director is commanding PITCH and ROLL during the rotation sequence, until you give it a lateral navigation mode, it will only command WINGS LEVEL. So...the answer is...you fly wings level until 400 ft without regard for heading or track. The important thing here is wings level, not drift. Then at 400 ft you select a roll mode (heading).
Heel-Judder@reddit
I have yet to fly with a single pilot in corporate, freight, or airlines, who has not asked for heading select [runway heading] at 400 ft AGL.
Mispelled-This@reddit
I’ve had Tower controllers yell at me for drifting over a parallel taxiway (or runway) due to a strong crosswind. So I started tracking the centerline and then turning to runway heading after DER, and they yelled at me for that too. There is no winning with some people.
nascent_aviator@reddit
Do your best. You should be able to see the runway for some amount of time after lifting off. Even at RVR 600 as long as the runway is well lit you've got a little bit of time to set up your crab angle.
If you're taking off in true 0/0 I guess just pray you don't hit anything?
nascent_aviator@reddit
It is, though. In a strong crosswind you need to be crabbing into the wind immediately after takeoff. You need to maintain this until you're at least above any obstacles close to the runway (glideslope antenna, plane holding short or on a taxiway). After that you turn to runway heading. It's a turn, so that means 400 AGL.
CorporalCrash@reddit
Right off the ground. You don't track the centerline just after takeoff, you rotate on runway heading and hold it until they say otherwise. If you drift you drift, ATC takes it into account.
nascent_aviator@reddit
This will kill you in a strong crosswind. Say you have a 20 knot crosswind in a 152. If you doggedly keep the nose lined up with the runway, you will be hundreds of feet off the runway in a matter of seconds. Better hope you miss the glideslope antenna!
ATC takes drift into account for aircraft separation. They have no method to get obstacles out of your way!
CorporalCrash@reddit
The CAP GEN explicitly states:
"Departure procedures meet obstacle clearance requirements and are based on the premise that on departure an aircraft will:
Cross at least 35 feet above the departure end of the runway
Climb on runway HEADING to 400 feet AAE before turning
Maintain a climb gradient of at least 200 feet per NM throughout the climb to the minimum altitude for enroute operations.
I understand you're using FAA references and I'm using TC. I also read through the FAR AIM, and it does a pretty awful job of laying it out simply like the CAP GEN does, and doesn't specify to climb at runway heading.
TL;DR: this is OK, at least in Canada where I fly.
nascent_aviator@reddit
According to your reference, you fly above the departure end of the runway first. Then runway heading.
It doesn't matter where in the world you are. Flying runway heading as soon as the wheels lift off in a crosswind does not keep you from hitting the glideslope antenna, planes holding short, or any other obstacles that may be in the vicinity of a runway.
Once you are past the DER and above 35 feet, you have some protected airspace to either side of runway track. Until then, you don't.
CorporalCrash@reddit
So what do you do when you take off directly into cloud and cannot track the centerline to the DER?
nascent_aviator@reddit
Do your best with what you have. Unless you're taking off into 0/0 you don't lose visual references the moment the wheels lift off. If the conditions are so poor that you can't track the runway centerline even momentarily and you don't have avionics that can help with that, reconsider how badly you need to take off!
Substantial-End-7698@reddit
It’s also your responsibility to comply with ATC instructions/clearances and advise ATC if it’s unsafe to do so. So if you can’t maintain runway heading right away, then technically you should be advising tower. Flying runway track instead is not correct.
Realistically though, if you’re that concerned about obstacles beside the runway, just track the centreline until you’re comfortable that the obstacles are out of the way and then fly runway heading as soon as able.
nascent_aviator@reddit
If you're instructed to "fly heading 300" on a departure, from runway 21, do you immediately turn left the moment you leave the ground, or do you wait until 400 AGL?
Motriek@reddit
Lowly PPL recent IR. Was tought during initial instruction to stay over the runway until DER, but I can't find that in regs. Realize that's not possible when climbing into soup.
Bot_Marvin@reddit
400' above the DER just like any other IMC turn is my best guess.
Urrolnis@reddit
That's when my aircraft switches from a takeoff lateral navigation mode to heading select or LNAV.
You really won't be yanking and banking below 400' AGL, it's usually just runway heading up to that point as is.
OracleofFl@reddit
Question: So when you are climbing to 400 you should maintain extended centerline then switch to heading mode?
notaballitsjustblue@reddit
Yes. Unless stipulated in your OMC or equivalent. Like at St Maartin.
Repulsive-Loan5215@reddit
u/vetements_coat
-burnr-@reddit
My aircraft is in HDG mode at the beginning of the takeoff roll and that’s what I would fly up to 400’, then Otto will fly the rest.
What kind of shitty flight director forces a takeoff in roll mode?
Heel-Judder@reddit
The answer is 100% at 400' above DER unless there are extenuating circumstances (i.e. company pages, ODP, noise abatement, etc).
hondaridr58@reddit
Unless it is a Serco contracted tower. At Serco control towers they tell you to fly runway heading on departure, then proceed to yell at you frantically, saying "FLY RUNWAY HEADING! TURN LEFT 15 DEGREES!!"
"tower, do you mean you want me to fly extended centerline?..."
"AFFIRMATIVE! LIKE I SAID! FLY RUNWAY HEADING!"
smh.
tennisfan1995@reddit
Same up in the great white north. Fly runway heading means,fly “runway heading”.
Rainebowraine123@reddit
Just to clarify, in Canada fly runway heading means runway course?
tennisfan1995@reddit
No. Just fly the heading. Ex: RWY07 has heading of 074 degrees magnetic, then fly a heading of 074 and not a course/track of 074. Same goes when you’re vectored as ATC factors in wind when giving you headings to fly.
F1shermanIvan@reddit
I just had this conversation with my FO in the plane today; she had the same question.
Lpolyphemus@reddit
If the instruction is “fly runway heading,” my nose doesn’t ever really get off that heading.
During the takeoff roll, it is obviously on runway heading and the aim is to keep it there as soon as I am airborne. It might for a moment during a sloppy rotation?
In true IFR it’s not unusual to lose all visual reference as soon as you are airborne. Don’t even try to fly visually unless there is a special instruction.
Mike__O@reddit (OP)
If you have a 15kt crosswind that would produce a drift angle of roughly 5 degrees at a ground speed of 180kts. I agree that the number on the top of the compass card shouldn't change, but your ground track certainly does. A runway represents a physically fixed ground track with an associated heading, but once you're off the ground you're subject to the other forces in play, namely the wind.
My question is when is it procedurally correct to transition from that fixed ground track of the runway to the dynamic track of heading+drift.
Lpolyphemus@reddit
It appears as though you and I agree.
To quote you, “I agree that the number at the top of the compass card shouldn’t change.” In other words, you hold the heading same heading throughout the takeoff and initial climb.
Change in track will take care of itself as the wind does its thing during your climbout. If you are 5° off runway track while 100 feet in the air, so be it as long as you are maintaining runway heading.
With that said, good choice during the debrief. Anything to get out of the building quickly and on your way home.
Heel-Judder@reddit
You're not flying a heading or a track when taking off. You are flying pitch (whatever for your airplane, say 20°), and roll (wings level). Then at 400 feet, you transition roll modes from wings level to heading mode. Your heading may have strayed off runway heading by one or two degrees because the airplane probably weathervaned a bit during/shortly after rotation.
JadedJared@reddit
Had a 35 kt crosswind on takeoff a couple of days ago, in addition to flying pitch and wings level I’m also tracking the runway so I don’t drift much. That bitch weather vaned like a motherfucker on lift off.
Heel-Judder@reddit
If you're making an effort to track the runway, then you're obviously using some bank, which goes exactly against what you just said of "flying pitch and wings level."
JadedJared@reddit
True dat
Heel-Judder@reddit
I never flew the 320, only the 350. So I don't know exactly how the flight director works or what the roll mode is on rotation when you're planning a heading departure.
Headoutdaplane@reddit
You are supposed to drift. That is Rwy Heading on take off is assigned. The reason is if there are parallel runways, with a direct crosswind, and the downwind plane flies runway track (correcting for the crosswind) while the upwind plane is flying runway heading, the upwind plane can drift into the downwind planes buffer.
Now if both planes fly runway hdg and drift down wind the separation is maintained.
Headoutdaplane@reddit
That depends on company procedures, we take off in hdg and speed.
Lpolyphemus@reddit
Fair enough.
Heel-Judder@reddit
...at 400 ft.
Substantial-End-7698@reddit
You keep saying the same thing but you’re assuming that the modes on all planes work the same way, which isn’t true. FWIW, the 737 works completely differently from how you’re describing it (LNAV at 50 feet) and that’s the most common airliner around…
oranges1cle@reddit
You’re thinking about this way to hard. Bug runway heading, fly it.
Alfvenskus@reddit
OK, I’m gonna throw the wrench in here… 400 feet is where you change your heading. If you are assigned heading 350 and you are taking off on 27, you maintain 270 until 400 feet then turn. Until that point, you always fly runway heading. From rotation. However, there is enough clearance from ground or airborne obstacles if you track the runway to the end or not.
Heel-Judder@reddit
You don't maintain 270 until 400 ft. You maintain wings level until you select a roll mode. That's what the flight director is commanding. Wings level takeoff pitch.
Alfvenskus@reddit
Not sure what flight director you are talking about, in most of the aircraft I teach, either heading or nav is selected for lateral mode. And in nav mode, the a/c will most of the time maintain heading until 400 feet. But I am sure this is not universal.
Substantial-End-7698@reddit
That’s not universal. For example the 737 will immediately command runway heading in this case once airborne. So assuming you stick to the flight directors (which you’re expected to do) then you will turn away from the wind to return to runway heading shortly after liftoff. In other words, maintaining wings level until 400’ is the wrong thing to do.
It’s easy to not even notice this happening to yourself unless there is a stiff crosswind, but if you’re ever lined up as the previous departure rotates you’ll be able to see this happening very easily from that perspective. You’ll see them lift off, weathercock into the wind, and then begin a turn downwind to fly runway heading. All below 400 feet. My home base frequently does closely spaced visual separation departures so I witness this all the time.
PaperPlane36@reddit
Not a 737 driver, but I believe that Wings Level vs Heading Select off the ground is a customer/operator choice and may vary from airline to airline.
Substantial-End-7698@reddit
That is true, but in either case most of the time you’re going to be taking off with LNAV armed. That kicks in at 50’. I was just trying not to get too technical.
Oregon-Pilot@reddit
Thank you for asking about this. I’ve been wondering about this for some time myself. Lots of various answers in here, but like you, I want a source.
This post inspired a deep dive. My legacy 757 FM says during xwind takeoff, “apply light upwind aileron to maintain wings level and downwind rudder as necessary to maintain runway tracking…recover from sideslip…” which makes sense and feels natural to me. So then we are wings level, roughly tracking centerline for a moment, but is our FD commanding to follow centerline track, or the track when we lifted off, or no track at all? I can’t find the answer in the book.
The book confirms GA mode commands your current track, but in TO, it might just be wings level, and no track whatsoever. My notes from qual training are that TO roll mode tracks whatever the airplane is doing at liftoff. Instructor info is nice, but I’d love to see an official book answer on this.
I might reach out to the fleet experts at my airline about this one because it’s kind of important.
Head_Visit849@reddit
They said “fly runway heading” Not “track the runway course”. They know you will drift. The idea is that everyone drifts together
Mike__O@reddit (OP)
I understand that. My question is WHEN do you start that drift? Based on the replies, there doesn't seem to be a super-firm consensus. 400 AGL seems to be a pretty common response, but it becomes a bit more ambiguous when you start asking lateral questions. Some replies (as well as my previous Air Force training) say 400 AGL AND past the departure end of the runway (if it can be identified), while other replies have said 400 AGL no matter where you are reference the DER. Some have even said "when you break ground" which I don't think is the correct answer.
Substantial-End-7698@reddit
In both Boeings I’ve flown if the FMC is programmed to track runway heading, then once LNAV engages at 50 feet the flight directors will command runway heading. And that’s what you do, a gentle turn back to the runway heading. So not as soon as you “break ground” but late enough that wing clearance isn’t an issue particularly if you lose an engine.
In other words, Boeing’s answer is that they expect runway heading from 50 feet. I can’t speak for Airbus but I’d bet it’s similar.
nolifepilot@reddit
They changed the 202v3 in the last year or two, it's now just 400 ft AGL, there's no longer any requirement to be past the departure end.
Mike__O@reddit (OP)
Thanks. I got out in 2018, so my experience is dated
nolifepilot@reddit
Very jealous, counting the days haha
Mike__O@reddit (OP)
Pirep: the grass is indeed greener
randombrain@reddit
As a controller, I think that if you're in anything slow enough for there to be a significant discrepancy between "400 AGL" and "over DER" I'm going to be giving you more spacing anyway. I'm not going to roll a Phenom one mile behind a Skyhawk in hard IFR, no matter what headings I assign them. (I might roll a Phenom a mile behind a Skyhawk if the Skyhawk is VFR and I told them to start an early turn and I observe them doing it.)
If you're in any kind of a jet with any kind of decent performance, from a controller perspective it doesn't make a gigantic difference to me. Sometimes a smaller/lighter jet will start cranking the yoke over when they're only three-quarters of the way down the runway and that's okay.
Heel-Judder@reddit
How do you know when you've reached DER when you're in 600 RVR? How do you know you're tracking the runway centerline? You rotate wings level to 400 ft and then you select a roll mode. My god, man. What did the air force do to you?
Head_Visit849@reddit
Ahhh I see what you’re saying
JadedJared@reddit
Not that close to the ground. I’m runway track until 400.
Substantial-End-7698@reddit
In both Boeings I’ve flown if the FMC is programmed to track runway heading, then once LNAV engages at 50 feet the flight directors will command runway heading. And that’s what you do, a gentle turn back to the runway heading. So not as soon as you “break ground” but late enough that wing clearance isn’t an issue particularly if you lose an engine.
In other words, Boeing’s answer is that they expect runway heading from 50 feet. I can’t speak for Airbus but I’d bet it’s similar.
nascent_aviator@reddit
When you are assigned a heading on an IFR departure (whether "runway heading" or "heading XXX") you are expected to wait until 400 AGL to turn. If you drift off the runway too low TERPS no longer guarantees you obstacle clearance and you could very well hit the glideslope antenna.
TheGacAttack@reddit
400' and DER. As I understand it, it's BOTH of those things. So if your performance puts you at 400' AGL with 1500' of runway remaining, then you're not yet transitioning to your assigned heading.
Is that correct? Or am I wrong? (I honestly don't know-- that's just how I've been interpreting and applying it)
chuckop@reddit
The Opposing Bases podcast covered this recently. It’s always heading. The wind affects everyone.
They said that they - as controllers - rarely need aircraft to fly a particular ground track. It’s usually headings and Direct-To.
abcd4321dcba@reddit
400’
/thread
propell0r@reddit
After you rotate and you let the aircraft weathervane into the wind, you now have a heading error and need to correct it ASAP back to runway heading if “fly runway heading” was your instruction. At 400ft, you can turn wherever you want to with respect to your IFR clearance. Your track over the ground does not matter with that clearance.
yeahgoestheusername@reddit
I think it’d be 400 AGL as others have said. But isn’t “heading” a misnomer here in that fly runway heading means to correct for wind and fly a straight out course from the runway? I’d imagine departing on the right runway and drifting over to the left runway would be the reason. Learning IFR so please correct me if I’m wrong here.
brongchong@reddit
400’
andrewrbat@reddit
You only need to maintain runway track with crosswind correction(essentially a slip) until airborne. The plane will weathervane somewhat as soon as you release crosswind inputs which is basically when you lift off.
Procedurally you turn to assigned headings or procedural headings at 400’, yes and the controllers (and airport design features )protect the airspace around the runway from causing a crash when you follow this procedure. When theres an exception to fly rw heading sooner than 400’ it will be due to obstacle clearence.
Galvanizedddd@reddit
Right away, why are you looking outside so long? If you're taking off in RVR 600 how are you going to track centerline? You aren't, in the plane company SOP says no XW inputs because roll is aided with spoilers and we are in GA mode on takeoff. Wings should be level right from rotation allowing the drift from the wind.
Maintain runway heading, you started on runway heading on the ground so why did you turn to maintain rwy track below 400 and without being told?
Heel-Judder@reddit
It's as simple as you said. When we rotate, we maintain wings level and takeoff pitch. Wings level prevents loss of lift at the most critical time. The airplane will naturally weathervane into the wind during the rotation sequence. At 400 ft, you select a roll mode (runway heading in this case), and you adjust a few degrees to get back on runway heading.
Galvanizedddd@reddit
I think they're talking about significantly more than a few degrees. Nobody is flying perfectly in windy conditions to a few degrees. I would not allow a weathervane of 10 degrees off rwy heading.
Heel-Judder@reddit
A 200,000 lb jet is not going to weathervane 10 degrees, my guy.
Galvanizedddd@reddit
That's what I'm saying...the post is talking about a weathervane a lot more that would actually happen. A degree or two is not something you even consider.
Heel-Judder@reddit
A typical weathervane can be anywhere from 2-5 degrees. And that doesn't matter. Your entire focus is to keep the wings level. That's all that matters. Weathervaning does not matter. Tracking centerline does not matter. Wings. Level.
Galvanizedddd@reddit
I agree, that's what I was trying to convey.
Rictor_Scale@reddit
Where I fly these instructions are usually for just a mile or two and we are stuck under a shelf at 1000. But I just called local ATC and told them they were down-voted by Reddit and should start allowing departing planes to collide with incoming traffic on long downwinds packed with students flying the downwind ground track.
the37ngskibidi@reddit
Depends on the airline, normally 400’AGL reaching departure end of runway. Some airline procedures say differently so follow those if you have them. For example, 1000’ AGL if in IMC, 400’ AGL in VMC
SparkySpecter@reddit
On that clearance I fly over the runway until I pass the threshold and then navigate off the runway heading.
One_Event1734@reddit
Good luck with that flying a jet with 20° pitch up in OVC001.
Urrolnis@reddit
Lol did they suggest looking back at the runway behind you?
One_Event1734@reddit
Yes they did, but I let my X-ray vision cert lapse. So frustrating.
Urrolnis@reddit
Ugh hate when that happens
bisquick__@reddit
From what I understand, When ATC assigns a heading, they’re really looking at your ground track and will make adjustments based on winds if you’re going where they don’t want you to go. Do what you normally do with a crosswind and let atc let you know when to correct your heading.
CMIIW
rFlyingTower@reddit
This is a copy of the original post body for posterity:
I've been flying for a long time and still trying to learn things. This particular question came up during a sim I had recently. It was never debriefed because I met the evaluation standards and I didn't want to open any cans of worms.
So say you're taking off with a fairly strong crosswind. Your departure instructions are "fly runway heading, climb and maintain 5000"
We all [should] know that assigned headings are where they want you to point the nose, and the pilot should not apply drift corrections to an assigned heading.
When taking off IFR with a strong crosswind, you will eventually need to remove your crosswind controls and allow the airplane to weathervane into the wind. Removing those crosswind controls and pointing the nose to runway heading will result in a downwind drift that will take you off the extended runway centerline.
So my question is when is it procedurally correct to transition from maintaining runway centerline to flying the assigned runway heading? In my sim I did it passing 400' AGL, but this resulted in me being a decent bit off runway centerline by the departure end.
What is the procedurally correct answer here?
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