ANALYSIS: 2014-05-02.. Controller Error at KLAS

At approximately 2:33PM, on Friday 5/2/2014, the controller at Las Vegas Tower [KLAS] cancelled the takeoff clearance for a Delta Boeing 737. The Delta flight crew had started their takeoff roll (with ‘no delay’, per ATC’s direction) approximately 39-seconds earlier. The flight crew immediately aborted the takeoff, hit the brakes hard, and was able to taxi off the runway at Taxiway A5. In the process, the brakes overheated and two tires went flat, according to an NBC News article.

20140502-KLAS

The RWY19R arrival is marked in red (N702DM exited at Taxiway W, at the south box); the RWY25R departure is marked in green (Delta2483 aborted, then exited at Taxiway A5, at the west box).

So, how did this happen?

00:33.. the controller cleared an arriving GLF3 (N702DM, on a visual to a left base) to land RWY19R.
01:10.. the controller cleared Allegiant564 to takeoff RWY25R.
01:15.. the controller cleared Delta2483 to ‘Line Up and Wait’ RWY25R.
02:05.. the controller cleared Delta2483 for a no delay takeoff, with visual separation on the preceding Allegiant departure.
02:44.. the controller cancelled takeoff clearance for Delta2483.
03:04.. the controller issued taxi instructions to DAL2483, via A5 to resequence for another takeoff.
03:22.. the controller tells DAL2483, ‘sorry about that’.
03:42.. the controller instructs Gulfstream N702DM to turn right at Taxiway W (and the pilot’s reply was he might not make the turn).

It appears it was a Controller Error. Specifically, two minutes and ten seconds prior to the abrupt cancellation of the Delta takeoff clearance, the controller had cleared a Gulfstream III jet to land on Runway 19R. So, at the time of the cancellation, the Gulfstream was on short final to land Runway 19R, while the Delta B737 was close to full speed and possibly even airborne. Both flights were aimed toward the intersection of the two runways. The controller was failing to protect a possible collision, in the event that the Gulfstream pilot aborted their landing and did a ‘go around’. The audio for this incident was archived at LiveATC.com (see side-box for timing of key events). When the controller  recognized the conflict, he had  to make a split-second decision: either cancel the takeoff clearance, or alert both aircraft of the conflict and get them to see each other (and turn, if necessary) to avoid a collision. Because Runway 25R is exceptionally long (14,000 feet), the controller could safely consider cancelling the takeoff. If this had been a more typical runway (say 7,000 feet or shorter), a cancellation would have been extremely hazardous, and could have resulted in a crash off the end of the runway. This flight was loaded with at least four hours of fuel to fly all the way to Atlanta, so any rupture could have produced a substantial fire. At the time of this incident, KLAS was in a west flow. In this configuration, commercial airlines typically use Runways 25R & 25L, while General Aviation uses Runways 19R & 19L. The tower controller’s focus is on timing. He/she normally directs commercial arrivals onto Runway 25L, then holds them south of Runway 25R. Commercial departures are loaded onto Runway 25R (often using ‘Line Up And Wait’ phraseology, followed by ‘Immediate Takeoff’ or ‘No Delay’ instructions). The GA flights use Runways 19R and 19L for a very practical reason: these runways are miles closer to where the GA aircraft park, on the ramps in the western part of the airport. So, ATC’s focus is simply to time each clearance, to ensure no conflicts happen where the runways intersect, or where taxiing aircraft cross active runways. In this incident, it appears the controller simply became too focused on his handling of commercial arrivals and departures on Runways 25R and 25L, and he ‘forgot’ his Runway 19R arrival.

Rejected Takeoffs can result in flat tires

Wiki’s entry about ‘Rejected Takeoffs’ says this: “Before the takeoff roll is started, the autobrake system of the aircraft, if available, is set to the RTO mode. The autobrake system will automatically apply maximum brakes if throttle is reduced to idle or reverse thrust during the takeoff roll.” Thus, if ATC cancels takeoff clearance and the flight crew elects to comply, they will immediately reduce thrust and brakes will go to maximum. This, coupled with the large amount of kinetic energy to stop the airplane, will excessively heat the brakes and cause the tires to go flat … which is what apparently happened at this incident. Online comments by witnesses indicate that the aircraft stopped on the ramp area, and airstairs were brought out to offload the passengers. Online comments also indicate the B737 remained at this remote location for hours before it was relocated. The passengers were delayed for roughly four hours, awaiting a replacement aircraft.

The real damage is in the PR spin

Just a week earlier, a very similar incident happened at Newark [KEWR], when a landing United B737 was sent around and a departing regional jet had to nose down to fly underneath, at the runway intersection. Perhaps because of the KEWR near-collision, FAA was quick to spin the details of the KLAS incident. That spin came in the precise phrasing of details so as to imply that this was ‘precautionary’ and a ‘pilot-initiated rejected takeoff’, and making no hint at the possibility of a controller error. Here is an excerpt from the NBC News article, indicating FAA is the source of this PR spin:

 “Controllers canceled the Delta jets’ takeoff clearance as a precaution,” Federal Aviation Administration spokesman Lynn Lunsford told News 3 in an email on Saturday afternoon. “A preliminary analysis showed that safe separation would have been maintained. The canceled takeoff clearance was precautionary.” Lunsford said the event is being reviewed, adding, “Our preliminary review of the radar data showed there was no conflict.”

Wouldn’t it be nice if FAA…

…could become transparent about this type of incident? There were 160 passengers on board, all of whom endured the shock of a sudden deceleration during takeoff, and none of whom had a view to see if they were about to hit something or crash off the end of the runway. Likely, many of them were afraid their lives were about to end. Thousands of others saw what happened, and many of them used personal devices to snap images. The world has the audio posted online (as it should be). Online discussions are happening (discussion at AirNation). Most of the story is out there, and yet now the story is becoming how desperate FAA remains with their need to ‘manage’ the story. So, why in hell is FAA still playing coy? Why will FAA collect ATSAP filings from the FAA personnel involved, then ‘bury’ all statements into the ATSAP Black Hole, pretending the Public should not see them? This is wrong, FAA; time to clean up your act.

UPDATE, M/D/Y: — In a news article posted on 5/5/14, FAA spokesperson Lynn Lunsford backpedaled, confirming the involvement of the Gulfstream III landing Runway 19R.