The 1977 accident at Tenerife hangs over the aviation industry like a pall, and preventing a repeat is the goal.
Recall the specifics: at Tenerife, in the Canary Islands, two Boeing 747s were on the runway at the same time, the KLM jet, waiting to take off and the Pam Am aircraft, taxiing down the runway (backtracking, is the operative expression). The taxiways at the far end of the runway were clogged by parked aircraft.
The Dutch captain, anxious to get in the air before crew duty time limits would preclude the flight, applied takeoff power as the Pan Am jet was turning off the runway onto a taxiway. The Pan Am crew was intending to turn back onto the runway to take off after the KLM jet, but was in the path of the KLM jet.
The following exchange, captured by the cockpit voice recorder (CVR) between the Dutch flight engineer and captain, is instructive:
Flight engineer: Is he not clear then?
Captain: What do you say?
Flight engineer: Is he not clear, that Pan American?
Captain: Oh, yes (emphatically).
Seven seconds later, the KLM jet rotated, and about six seconds after that the captain uttered an exclamation as the Dutch jet ripped through the top of the Pam Am aircraft. In the fiery impact, 583 people on the two aircraft died. It remains to this day the worst single accident, in terms of death toll, that has ever occurred in aviation.
Ever since, the risk of a runway collision has been couched in terms of the Tenerife disaster. For example, at an FAA runway safety summit a few years ago, Professor Arnold Barnett of the Massachusetts Institute of Technology said that the risk of a runway collision in the United States could take more lives than all other factors combined. The National Transportation Safety Board (NTSB) has investigated any number of runway close calls that, but for a few feet or seconds difference, could have ended in a Tenerife-type fiery collision with shards of aluminum and bodies littering the runway.
Another potentially dangerous situation is unfolding at Indira Ghandi Airport in New Delhi, India. Some runway incursion events there are being attributed to the unavailability of taxiways due to construction in progress, and the runway being used compulsorily for backtracking aircraft.
It may well be that takeoff clearance has devolved to pro forma ritual, the safe execution of takeoff checks, briefings, and the takeoff itself being paramount. Perhaps it would be useful to add a time dimension to make takeoff clearance more noteworthy. Consider the present situation:
Controller: "Continental 743, wind 240 at 15, clear for takeoff, right turn as soon as possible and call departures on 132.95."
Readback/Response: "Continental 743 cleared takeoff, early right turn and departures on 132.95."
Proposed:
Controller: "Continental 743 clear takeoff time 43, call departures passing 4000."
Readback: "Continental 743 clear takeoff time 43, departures at 4000."
By this means, takeoff clearance would be accorded a time qualifier that would make it much more memorable for pilots.
It may be possible to take yet another step. For example, it should be de rigueur to actually switch "on" the air traffic control transponder in the aircraft only after or as receiving the takeoff clearance. The act of transponder activation usually illuminates a light on the transponder panel, but too often that’s down and out of view. However, if a repeater of that light was prominently in the view of each pilot, one would now have a de facto Go/No Go traffic light. Thus, upon receipt of takeoff clearance, the pilot not flying would switch on the transponder.
Two positive actions would be necessary to complete and confirm the takeoff clearance, and the ritual Go/No Go light in front of each pilot would wink out on nosewheel oleo extension at rotate.
Moreover, the transponder is a universal fitment these days, it would be unusual to have it inoperative (per the minimum equipment list), and it readily provides an apt solution to the positive action needed on receipt of takeoff clearance. To be sure, this procedure could become an International Civil Aviation Organization standard, although that would take both industry consensus and time. Or operators could enact this transponder confirmation procedure as a standard operating procedure. Over time it could become a de facto standard.
Having a couple switched-on pilots getting it wrong is doubtful, and there are enough potential Tenerife disasters occurring to warrant positive action to obviate an error made almost daily in aviation–taking off without clearance.