Re: [SystemSafety] Chicago controller halts Delta jet's near-miss on takeoff: '1328, stop, stop stop!'

From: Les Chambers < >
Date: Sun, 21 Jun 2015 09:28:36 +1000

It seems to me that the ATC - Pilot voice protocol is missing a step. Basic principles:
1. The ATC must be made aware of the pilot's intention to roll his aircraft.

2. The Pilot must not act on this intent without explicit approval from the ATC. In concept, a safer protocol might look like this: ATC: You are cleared for takeoff
Pilot: My understanding is that I am cleared for takeoff ATC: Your understanding is correct

A high-level design might look like this:

[aircraft state: positioned for takeoff]

	|Message 1. ATC : Southwest 3828 cleared for takeoff
[aircraft state: takeoff enabled]
	|Message 2. Southwest 3828 Pilot:  Southwest 3828 clearance to roll 
[aircraft state: pending approval] 
	|Message 3. ATC : Southwest 3828 cleared to roll 

[aircraft state: taking off]

The Southwest pilot would have to misunderstand two ATC clearances for this to fail.

I could not find the exact text of the conversation between ATO and pilot in the Chicago case study so, in search of ATC/Pilot voice protocols in common use, I reviewed Sully Sullenberger's book: Highest Duty: My search for what really matters, which has the NTSB cockpit voice recorder transcript in an appendix. This transcript is now available at:

To summarise:
{15:24:54}ATC: Cactus 1549 runway four clear for takeoff.
{15:24:56.7}Sullenberger: Cactus 1549 clear for takeoff
{Take off Dialogue between pilot and copilot}
{15:25:45}ACT: Cactus 1549 contact New York departure, good day.
{15:25:48}Sullenberger: good day.

In this dialogue, the lack of a third exchange as per message 3 above seems remarkable. I note also that Sullenberger did not repeat the authorised runway ID in his acknowledgement (refer Bonus material two below). This seems a tad dangerous.
Am I missing something?


PS bonus material:

Bonus material one:
I draw your attention to -->, refer to the following timestamps :
{15:27:10.4} Sullenberger: birds.
{15:27:11} Copilot: whoa.
{15:27:11.4} Cockpit area microphone: [sound of thump/thud(s) followed by
shuddering sound]
{15:27:12} Copilot: oh #.
{15:27:13} Sullenberger: oh yeah.
{15:27:13} Cockpit area microphone: [sound similar to decrease in engine
noise/frequency begins]
{15:27:14} Copilot: uh oh.

"{15:27:12} Copilot: oh #." Really??? These men are heroes, gods almost. Surely their every word, including explicatives, which must have been sublime, are worthy of inclusion in the Canon of heroic deeds.

Bonus material two:
On August 27, 2006, a Bombardier Canadair Regional Jet 100ER crashed while attempting to take off from Blue Grass Airport in Fayette County, Kentucky. The aircraft was assigned the airport's runway 22 for the takeoff, but used runway 26 instead. Runway 26 was too short for a safe takeoff, causing the aircraft to overrun the end of the runway before it could become airborne. It crashed just past the end of the runway, killing all 47 passengers and two of the three crew.

In 1993, a commercial jet at Blue Grass Airport was cleared for takeoff on Runway 22 but mistakenly took Runway 26 instead. Tower personnel noticed the mistake and canceled the aircraft's takeoff clearance just as the crew realized their error. The aircraft subsequently made a safe departure from Runway 22.[49]

In January 2007, a Learjet was cleared to take off at Blue Grass Airport on runway 22, but mistakenly turned onto runway 26. Takeoff clearance was canceled by the local controller prior to the start of the takeoff roll.[50]

On October 31, 2000, the crew of Singapore Airlines Flight 006 mistakenly used a closed runway for departure from Chiang Kai-shek International Airport, Taipei. The Boeing 747-400 collided with construction equipment during the takeoff roll, resulting in the deaths of 83 of the 179 passengers and crew on board.

-----Original Message-----
From: systemsafety-bounces_at_xxxxxx [mailto:systemsafety-bounces_at_xxxxxx Peter Bernard Ladkin
Sent: Friday, June 19, 2015 3:52 PM
To: Simon Whiteley
Cc: systemsafety_at_xxxxxx Subject: Re: [SystemSafety] Chicago controller halts Delta jet's near-miss on takeoff: '1328, stop, stop stop!'

Prof. Peter Bernard Ladkin, University of Bielefeld and Causalis Limited

> On 18 Jun 2015, at 19:37, Peter Bernard Ladkin <ladkin_at_xxxxxx
> A known problem. Quasi-ambiguous call signs.

As Chris says, not particularly rare.

Steven Cushing's Fatal Words, a book published by U. Chicago Press nearly two decades ago on safety problems in civil aviation caused through linguistic factors, has a chapter on it, I recall (I am away from my library).

Contributing factors are moderately clear. One is similar call signs. Another is transmissions being "stepped on" (partially obscured by a concurrent transmission from another). The third is cognitive confusion of some sort - someone gets the airplanes mixed up as a result of the first two. It is surprising that the issue persists after decades of attention from smart people.


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systemsafety_at_xxxxxx Received on Sun Jun 21 2015 - 01:29:03 CEST

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