I've always been told that TODA* = TORA + Clearway. I can't really imagine what a negative clearway would be, so that leads me to think that it is required that TODA >= TORA. Interestingly, a colleague pointed out a certain airport (Invercargill, New Zealand - ICAO code NZNV) where the declared distances published by a certain source describe a TODA that is in fact less than the TORA.

My colleague and I are under the impression that some kind of typographical error has occurred when this source was publishing the data. However, I can't help but think back to strikingly similar conversations we had after seeing a previously unheard of case where ASDA < TORA. As it turned out, the FAA had changed how Runway Safety Areas were considered, in such a way that it is totally possible for ASDA < TORA (and we've been seeing it more and more frequently ever since).

*TODA = Take-Off Distance Available
TORA = Take-Off Run Available
ASDA = Accelerate-Stop Distance Available


I wanted to see if anyone has ever heard of any other case where TODA < TORA, under any regulatory agency. What would the rationale be if that were the case?

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    $\begingroup$ If runway has obstacle at the end maybe then TODA < TORA? Taking opposite way TODA will be > TORA. $\endgroup$
    – Andrius
    Commented Feb 2, 2016 at 21:32
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    $\begingroup$ Can you be less mysterious about the "certain" airport and sources? A specific example could be very helpful here. $\endgroup$
    – Pondlife
    Commented Feb 2, 2016 at 21:43
  • $\begingroup$ Since different Civil Aviation Authorities could, at least in theory, use different definitions of TODA/TORA/etc., it would probably be good to phrase this question in the context of just one country's regulations, at least if the title question is what you're wanting to know. $\endgroup$
    – reirab
    Commented Feb 3, 2016 at 20:06
  • $\begingroup$ @reirab: Good point. I guess I'm curious if anyone is aware of any CAA anywhere that would allow for this. Updated. $\endgroup$ Commented Feb 3, 2016 at 21:26

2 Answers 2



Takeoff Distance Available (TODA) can never be shorter than Takeoff Run Available (TORA).

AIM 4-3-6

Takeoff Distance Available (TODA) – The takeoff run available plus the length of any remaining runway or clearway beyond the far end of the takeoff run available.

I had previously downloaded the FAA runway database and determined there is no TODA less than TORA. The mysterious airport may have incorrect data or the database is incorrect.

FAA Airport Information

The same database shows that approximately 14% of the runways have an ASDA shorter than TORA. Multi-engine pilots need to be aware of how their aircrafts performance was created and how to apply the correct declared distances.

  • $\begingroup$ I've updated my OP - the airport was Invercargill, New Zealand - ICAO code NZNV. I wonder if being an international airport makes any difference. $\endgroup$ Commented Feb 3, 2016 at 14:23
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    $\begingroup$ @GeneralMike Well, it does at least mean that the AIM and FARs are irrelevant, but NZ's CAA appears to use the same definition of TODA, according to Part 1 of their Civil Aviation Rules (PDF). $\endgroup$
    – reirab
    Commented Feb 3, 2016 at 20:02
  • $\begingroup$ Looking up declared distances from APG show these values for runway 4 at NZNV: TORA 7087 ft, TODA 7284 ft, ASDA 7087, LDA 6660. Runway 22 values at NZNV: TORA TODA ASDA all 7251 ft, LDA 6693 ft. Their AIP is not very helpful. $\endgroup$
    – wbeard52
    Commented Feb 4, 2016 at 0:30

What your question is essentially asking is, aside from the theoretical possibility that some nation uses TORA and TODA, but defines them differently from every other country, is there an airfield where there is an area designated as a take-off surface that is suitable for the take-off ground-run of an aircraft, but not suitable to fly over. That is clearly not possible.


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