[SystemSafety] ...Runway Incursion .... Tenerife 40th Anniversary

[Peter Bernard Ladkin]

I had some further correspondence with Simon about the Tenerife accident.

I though it was inappropriate to designate the Tenerife collision as a "runway incursion", since
both aircraft were cleared positionally to be where they were, so there was no unauthorised ingress.

I consulted the ICAO occurrence classification
http://www.icao.int/APAC/Meetings/2012_APRAST/OccurrenceCategoryDefinitions.pdf

There's RI with animals (RI-A) and RI with Vehicle, Aircraft or Person (RI-VAP).

RI-VAP says:

[begin quote]

Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle, or person
on the protected area of a surface designated for the landing and take-off of aircraft.

[end quote]

KLM 4805 was authorised to be where he was. Pan Am 1736 was authorised to be where he was. But KLM
was supposedly not authorised to take off even though he thought he was and ATC misunderstood the
readback (or whatever your favorite way of expressing these events is).

I approached Philippe Domogala for clarification. Philippe is a retired controller who worked at
Eurocontrol and was for many years chairman of IFATCA. He is intimately familiar with many accidents
involving ATC and the resulting developments.

Philippe said it wasn't a runway incursion (and expressed surprise that the Aviation Safety Network
WWW site so classified it). He said it is classified as a Collision, with a sub-category of Ground
Communications. He said further that one of the resulting changes in ATC-Aircrew procedures is the
terminology "Line up and wait" and the avoidance of the phrase "take-off" in any ATC transmission
except in the take-off clearance itself.

Another planned change was a technical device to prevent simultaneous transmissions. A system was
devised (e.g. CONTRAN) but was never mandated. A UK engineer, Nigel Corrigan, designed and worked on
Contran, convinced ATC, and some units did use it, but the airlines opposed it through IATA on
grounds of cost and resource allocation for pervasive implementation.

Philippe suggests that the crossed transmission, which preventing the KLM crew from hearing both the
controller stating they were not clear to take off and the PAN AM crew warning they were still on
the runway, was the key causal factor. I don't have any reliable mechanism as yet to prioritise
causal factors, but intuitively he seems to me to be right.

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
MoreInCommon
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de





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