Sufficient runway for an aborted takeoff
Posted by Person-man-guy-dude@reddit | flying | View on Reddit | 34 comments
One of my pre takeoff briefing involves engine abnormalities, I always say “if sufficient runway remains land straight ahead and use breaks as needed”, but what can you safely use to calculate sufficient runway? The 50-70 rule seems a little sketchy, so I’ve been using my calculated landing distance over a 50 ft obstacle for my departure runway. If something goes awry and I have that much distance left it should be ok right? But is there a more concrete and smarter way to determine if I can land safely or prepare for an off field landing? Thanks
usmcmech@reddit
Calculate your takeoff over 50ft + landing over a 50ft obstacle. That’s your “land back on the runway” distance.
ShaemusOdonnelly@reddit
Yes, but remember to calculate the landing distance with your take off config. In my school, we added a predetermined additional distance to account for reaction time.
makgross@reddit
No, it isn’t. Those are differently configured, and the speeds are different. Also, very few pilots do short field takeoffs and short field landings every time.
aftcg@reddit
Ah, yes this. I posted this myself but this is about as close as we can get. Add a few hundred feet for the oh shit factor and another few hundred for the extra speed.
haveanairforceday@reddit
That would be your "take-off from a standstill and land back on the runway" distance, right? So if you abort right after rotate then most of the takeoff distance you calculated is already behind you
DatSexyDude@reddit
Assuming a single engine plane? If the engine fails after takeoff, you’re landing. Regardless of the runway remaining. So it doesn’t matter.
If the engine doesn’t fail after takeoff, you aren’t landing.
Boom.
vtjohnhurt@reddit
You have a good chance of surviving rolling off the end of the runway. But if there's a nice hayfield on the far side of the fence, I might prefer that option. One should know one's options before starting the engine and visualize a plan. The bias towards landing on-airport has backfired many times. It's common to try to stretch a glide to make the runway after flying over a perfectly landable field.
haveanairforceday@reddit
Well there is the question of whether you are going to land straight ahead of find another clear area to set it down. If you are 300 agl you are probably better off picking a road or perpendicular runway/taxiway than trying to get back down on the same runway. Depending on how long your runway is, of course
primalbluewolf@reddit
Depends heavily on the type and how fast you're going at 300 ft. If you're in a sleek plane and high energy, you can probably make that 90 degree turn. In a typical light six cylinder plane at 300 ft and perhaps at a poorly-chosen Vy rather than a cruicr climb, you're not likely to even get through 90 degrees turn without bleeding off the speed you'd need for the flare.
In many 172s, in the right wind conditions from 300 ft you've a half decent chance of pulling off 360 degrees of turn and landing back on the original runway.
DatSexyDude@reddit
You are going to land straight ahead if you’re close to the ground and lose the motor. You will, it’s a fact.
You pick what looks good in front of you and land. Simple enough.
BluProfessor@reddit
You have to define "close to the ground". Most airports I fly in and out of have terrain straight ahead, you're better off turning in almost any situation you can't get it back down on the runway.
buzzly@reddit
But op posed as an abnormality, not a fail. Perhaps you notice the oil pressure is just below the green. Do you dive for the runway and slam on the breaks, or take your luck with a circuit in the pattern. At some point during the initial departure, it may make sense to continue. It’s going to depend on the abnormality and when it presents itself.
FunRaise6773@reddit
I think by abnormality, OP means loss of power. Me, if I have a gage out of the green and I’m climbing, I’m sticking close to the airport and trying to do a normal landing. Otherwise, it’s landing somewhere controlled.
theyoyomaster@reddit
What if you have an ejection seat? Also, what if you blow an oil line but are still producing usable but reduced thrust? Or, for that matter normal thrust but you suspect it could fail at any minute. If you have 5k feet of runway remaining are you taking your 152 up with an engine that might quit? What if you have 100 feet?
Person-man-guy-dude@reddit (OP)
lol that made it pretty simple
lnxguy@reddit
Brakes.
scottyh214@reddit
If you’re in a single, DatSexyDude is absolutely correct. If it’s a light twin that maybe is realistically incapable of climbing on one engine, many people use “positive rate, no-more usable runway, gear up”. What’s useable there? Right, wrong or otherwise, what I use is the runway I can see out the front window. If I can see the runway, I have a chance to land. If I can’t see it, it doesn’t exist.
bhalter80@reddit
Wheels up or wheels down? Wheels up you can get it to stop well under POH numbers.
What you're stumbling onto in the twin world is published as the accelerate and stop distance. It's the amount of distance to accelerate to rotation speed at gross weight, close the throttle and stop. Some twins also publish charts with a celebrate and go distances where you can lose the engine at rotation speed and still get off the ground and climb. My Baron is one of those for a small set of circumstances.
It's not published for a single so you're right on using takeoff distance + landing distance
R5Jockey@reddit
In a single? There’s no calculation to be done. You ain’t climbing if the engine dies. It doesn’t matter how far down the runway you are if you’re only 50 feet in the air.
makgross@reddit
The question is, do you dump the flaps and slip to a short landing, or pitch for best glide and go for distance? Because it takes A LOT more runway than most people here think.
There was a 206 with a failed engine at 50 feet at HHR a couple of years ago. They needed ALL the runway. 206s, especially the older G models like this one, can’t outfly a brick with a 300 HP engine. They land shorter than 172s. And take off pretty short too.
swaggler@reddit
I think you are over-thinking it. If you do not have sufficient runway remaining, you are landing straight ahead anyway (or dying).
On a recent instructor proficiency check, I was given engine failure at 100ft with 100 metres remaining. Nose forward, flaps 30, full side slip and hope for the best. You are going straight ahead regardless.
Tough_Roll9779@reddit
Multi engine large, you’re governed by V1. Single engine, look right, look left, look ahead, and pick where you’ll do the least damage to yourself and others. Multi light. Put the nose down (you won’t want to, but DO IT) get a little speed and a little climb. 100fpm climb is better than nothing. This was demonstrated to me GRAPHICALLY at Smyrna, TN (MQY), in a very tired BE58. But the best advice in this situation is what was told to me by our check airman at my first 135 job, “grab the biggest piece of what you’ve got left, and fly it to the ground.”
Flintoli@reddit
Hey I've flown into MQY. Small world. Lots of training there
aftcg@reddit
Use the take off to 50' distance and add the landing over 50' distance. In my Baron that's about 4600 at my normal weights. My homedrome runway is 3600.
moxiedoggie@reddit
Do you brief an abort point before you takeoff? If you have a good idea of your takeoff roll, you should estimate a visual point on the runway that you should be wheels up by and if you’re not, then you abort the takeoff. For instance. I have a 3500’ runway. In my C172, i should 100% be wheels up every time in all configurations and density altitudes by 1500’ down the runway. Now there is a taxiway intersection about 1500’ down the runway (or 2000’ if on the other end). I always brief that if I’m not wheels up and flying by the time I cross that taxiway down the runway I am aborting. Now, nicely this also gives me plenty of runway on both sides to come to a stop as well.
This works most cleanly if I’m still rolling on the takeoff roll. If I have taken off, and now I’m 50’ in the air, and then the engine quits. I got some split second thinking to do. That’s why I also brief, “anything abnormal happens less then 1000’ I’m landing straight ahead, no more than 30° to the left or right, shallow turns, best glide.” At 50' whatever runway remaining is always gonna be better than the trees at the end of the runway.
Also brief “anything abnormal greater than 1000’ turn back to airport land on anything possible runways taxiways grass etc”
22Planeguy@reddit
Well for an engine failure just after takeoff, you land and hope. But for an engine abnormality? Of course, it depends on the abnormality. In the case where there isn't a good chance of gaining enough airspeed and altitude, your approach is going to be pretty good. I'd even say you could go a bit further and shorten that decision distance.
In reality, those distances have a bit of margin built in, and in a scenario where the engine is imminently dying, I'd accept a small risk of going off the end of the runway at low speeds vs hoping that my engine keeps going long enough.
If your engine just burbled at 200 feet, obviously don't run off the end of the runway trying to put it back down.
The true answer is that it's going to depend on a lot of factors that are unique to the aircraft, pilot, and airport. It's difficult enough to have a black and white decision tree if you are familiar with all the variables. It's essentially impossible for anyone who doesn't. But knowing your landing distance from a specific altitude is a good place to start.
k12pcb@reddit
Fly it till it stops flying. What are you going to do? If you lose the engine and you have any space it’s better than what lies beyond because with no engine you are gliding until you are not gliding anymore.
Independent-Reveal86@reddit
Single engine with a low altitude failure you don’t have much control over how far you will glide, your main control is the direction you go and therefore the terrain you touchdown on. Personally I would rather land on tarmac and possibly have a low speed overrun than land on unknown terrain and risk a more substantial prang. So I would tend towards the remaining runway even if it’s not quite long enough. That’s but a hard and fast rule though, very situational.
Dangerous_Mud4749@reddit
You can use breaks to slow down. Particularly if the nose gear leg breaks, it'll help a lot.
But using brakes is better. Much cheaper to prep the aircraft for the next flight.
SubarcticFarmer@reddit
For an engine failure, the big thing is you need to have a floor where you will not attempt to turn around. I personally used my crosswind turn. Once I turned crosswind I could make the runway. Before that I'd be going somewhere else with at most bracketing corrections, so maybe 30 degrees from each side of course that you could get to with a gentle bank. The hardest part is you set your best glide and you don't deviate even if you are almost to a better landing site but barely short.
These days I theoretically shouldn't have to ever make that decision, but my altitudes for a turn attempt are much higher if it were to happen.
gromm93@reddit
Know the airport and the surroundings. Know when it's safe to land one way or another.
Figure this stuff out before you even get in the airplane, nevermind the runway.
If you really like, you can ask your flight school to let you try some scenarios in their simulator. Then you can test it all right to the ground.
Ok-Money2811@reddit
I wouldn’t go that deep into it. If there is sufficient runway ahead or there is not sufficient runway ahead, either way, at that low of an altitude, you are going to have to land on what’s ahead, runway or not. Turning could be a sure thing death sentence.
Even if it’s not enough to stop, you might be better off putting it on the concrete and run it off the end at a lower speed than crashing it into the woods near the airport. You might have an EMAS at the end of the runway, that’s also a good option to run it off the end and into.
Every take off is different and these days we have google/Apple Maps. It’s a lot easier to figure out options before you take off nowadays, even at unfamiliar airports, than it used to me. You have to just evaluate each take off.
pattern_altitude@reddit
This isn't really an exact science -- more a matter of whether you'd rather get the plane down and potentially overrun or if you'd prefer to keep flying and set it down off the field.
If I'm low enough to have a shot at putting it down at my home field, I'm getting on the ground every time. I'd much rather run through the airport fence than someone's living room.
rFlyingTower@reddit
This is a copy of the original post body for posterity:
One of my pre takeoff briefing involves engine abnormalities, I always say “if sufficient runway remains land straight ahead and use breaks as needed”, but what can you safely use to calculate sufficient runway? The 50-70 rule seems a little sketchy, so I’ve been using my calculated landing distance over a 50 ft obstacle for my departure runway. If something goes awry and I have that much distance left it should be ok right? But is there a more concrete and smarter way to determine if I can land safely or prepare for an off field landing? Thanks
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