During the last two days i flew four sectors. Three of them from intersection takeoffs. On one occasion an Airbus took an intersection that gave him an ever shorter takeoff roll than we had… It’s all a matter of flight preparation (or knowing your aeroplane well enough). Know your required takeoff distance and you will know, if an intersection takeoff is safe.
Regarding taking off in the wrong direction from an intersection: That has indeed happened a few times, even to airlines. On most line-up checklists, there is something like “Gyro – Check”. This not only means that one checks that the gyro aligns with the runway, but also, that it aligns with the correct runway.
And regarding the option to land back on the departure runway: What are the chances, that an engine will fail so shortly after takeoff, that landing back on the departure runway and stopping before the end (including reaction time, slowing down, putting the gear back down, setting flaps) is a realistic scenario? I think I will rather win the lottery twice before that happens. Of course on a runway closely surrounded by obstacles or absolutely un-landable terrain (Berlin Tempelhof was one of these) I would not waste a single meter of runway. But anywhere else I take the intersection takeoff.
What are the chances, that an engine will fail so shortly after takeoff, that landing back on the departure runway and stopping before the end (including reaction time, slowing down, putting the gear back down, setting flaps) is a realistic scenario?
Piston engine failure on takeoff is quite likely by my observation, most often due to some fuel starvation issue. Aborting after an engine failure to land on the same runway after takeoff has occurred to three people I know. It helps if you operate from a 5000 ft runway with an aircraft that takes off in a small fraction of that distance. On my private pilot check ride, the examiner pulled the power on me twice on the same runway so I ended up performing three takeoffs, short field, soft field and standard one after another. The runaway is about 8,000 feet long.
Now when flying from the same airport, I will accept an intersection takeoff that leaves me something like 3,000 feet to allow me to land if the engine quits due to bad fuel – the usual reason to go there is to top off the tanks cheaply. A friend often accepts an intersection which gives him roughly 1500 feet at the far end of the runway (i.e. 6500 ft behind him) versus taxiing all the way back from the fuel pump. I won’t do it…
Silvaire wrote:
so I ended up performing three takeoffs.
Does that qualify for the 90-day currency rule 
?? Couldn’t resist….
172driver wrote:
Does that qualify for the 90-day currency rule
Actually it would.
172driver wrote:
Does that qualify for the 90-day currency rule ?? Couldn’t resist….
JasonC wrote:
Actually it would.
If it was a tail wheel aircraft I believe you’d have to have come to a full stop on the runway before the second and third take offs
Steve6443 wrote:
Nobody has yet raised the best reason for taking the full length available – what happens if you have an engine failure directly after take off? If you’ve taken off from an intersection, chances are you’re landing off field.
That’s because it is not a particularly good reason. Would you have made the flight if the full runway length was equal to (or only slightly longer than) the required runway length? If yes, you would have deemed the chance of EFATO an acceptable risk – it would be no greater if you did a intersection takeoff from a longer runway.
Nobody has yet raised the best reason for taking the full length available – what happens if you have an engine failure directly after take off?
I did – in the original post.
That’s because it is not a particularly good reason. Would you have made the flight if the full runway length was equal to (or only slightly longer than) the required runway length? If yes, you would have deemed the chance of EFATO an acceptable risk – it would be no greater if you did a intersection takeoff from a longer runway.
That’s not a particularly good argument. Having a longer runway available that allows for an emergency landing within one of the most critical phases of flight is clearly an added safety margin (to what magnitude depends on the risk of an EFATO that early, which some argue is rather likely and others feel is rather unlikely). Accepting the risk of an EFATO on a short runway doesn’t mean I can’t consider that added safety margin if it is available.
Similarly, just because I find flying over mountain or water an acceptable risk, as you put it, doesn’t mean that in a situation where the opportunity presents itself to minimize the risk of a crash/ditching after an engine failure, I shouldn’t at least evaluate that opportunity and, if the conditions are right, use it (e.g. by flying a little further over land to minimize time over water). That’s comparable to accepting longer taxiways for a longer, saver runway.
One should not be complacent about EFATO. In the past 12 months I have had two incidents where after take-off from a short runway I would have landed back on given the option. One was fuel starvation and the other was smoke in the cockpit. Comparisons between commercial jets and single engine GA are irrelevant due to the known performance of commercial jets on one engine.
Even before these events I always took the view that runway before you is much better than runway behind you and these two events have done nothing to make me reconsider. I will ALWAYS take the maximum length available in my aeroplane.
Patrick wrote:
I did – in the original post.
Josh wrote:
It may also depend on the obstacles around the airfield – an intersection takeoff at an airport with fields around might be fine, but somewhere surrounded by buildings you might prefer a full length departure to gain maximum height over the upwind threshold
As did I, in the second post!
Ultimately, it’s an airmanship decision as to what margins of safety you are prepared to accept. Blindly saying “I always take the full length” is just as poor airmanship in my view as always taking the performance limiting intersection no matter what. If you are operating a piston single or twin out of a busy airport whose main business is heavy jet traffic it behoves you to make an effort to accommodate ATC requests. If you want every meter of a 2000m runway in all cases while regularly operating out of a 1300m runway (all other things being equal,) perhaps you ought to look at the validity of your personal risk assessments.
Steve6443 wrote:
Nobody has yet raised the best reason for taking the full length available – what happens if you have an engine failure directly after take off?
I did too here.
Steve6443 wrote:
If you’ve taken off from an intersection, chances are you’re landing off field.
Not necessarily true. It depends on how much runway is available and when the failure occurs.
For example if runway available is TODR+LDR and the engine failure occurs at 50’ or less, you should (theoretically) be OK. If it occurs above 50’, but below the altitude at which you can (safely) do a 180° turn and land on the opposite runway, you will end up in a field or at least somewhere else than on the runway
So if you want to remain 100% safe and avoid ending up in a field, you need enough runway to take off, climb to let’s say 700’ AAL and still be able to land straight ahead. That’s an awful lot of runway.
