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CRJ7 / C172, Allentown PA USA, 2008

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On 19 September 2008, A Mesa Airlines CRJ-700 making a night take off from Allentown in accordance with its clearance saw an aircraft ahead on the runway whilst accelerating at in excess of 100 knots and responded with a high speed rejected take off, clearing the other aircraft by an estimated 3 metres at approximately 40 knots. It was found that the TWR controller failed to ensure that the just-landed light aircraft had vacated the runway before issuing the take off clearance. This controller was newly recruited and recently certified in-position after supervised experience gained almost exclusively during daylight hours.
Event Details
When September 2008
Actual or Potential
Event Type
Human Factors, Runway Incursion
Day/Night Night
Flight Conditions On Ground - Normal Visibility
Flight Details
Aircraft BOMBARDIER Regional Jet CRJ-700
Operator Mesa Airlines
Domicile United States
Type of Flight Public Transport (Passenger)
Origin Lehigh Valley International Airport
Intended Destination Chicago/O'Hare International Airport
Take off Commenced Yes
Flight Airborne No
Flight Completed No
Flight Phase Take Off
Flight Details
Aircraft CESSNA 172 Skyhawk
Operator Private
Type of Flight Private
Origin Caldwell Industrial
Intended Destination Lehigh Valley International Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Landing
Location - Airport
Airport Lehigh Valley International Airport
Tag(s) ATC Training,
Aircraft-aircraft near miss
Tag(s) ATC clearance error,
Ineffective Monitoring
Tag(s) ATC error,
Incursion pre Take off,
Incursion after Landing,
Near Miss
Damage or injury No
Causal Factor Group(s)
Group(s) Air Traffic Management
Safety Recommendation(s)
Group(s) None Made
Investigation Type
Type Independent


On 19 September 2008, CRJ-700 being operated by Mesa Airlines on a United Express scheduled passenger service from Allentown PA to Chicago O’Hare IL made a high speed rejected take off on runway 06 upon seeing a light aircraft on the runway ahead at night in normal visibility. By veering to the left around it whilst decelerating, a collision was avoided. Following the incident, both aircraft taxied to parking, the jet requesting a maintenance inspection


An Investigation was carried out by the National Transportation Safety Board (USA) (NTSB). It was noted that Allentown did not have a ground movement radar system.

It was established that the privately-operated light aircraft, a Cessna 172 had just landed on the same runway and had been instructed to clear right at the first exit, ‘A4’, located at almost 450 metres from the landing threshold and stay on frequency. Half a minute later, the controller had cleared the CRJ700 for take off and a further half minute after that, the Cessna had advised that it was still on the runway having missed the turn off and asked to exit at taxiway ‘B’. The Controller had responded with “no delay…turn immediately” which had been acknowledged. The pilot reported that about three or four seconds later, the regional jet had passed to his left. He stated that he had not been aware of the issue of a take off clearance given to the other aircraft.

The CRJ700 crew reported that the Captain had been PF and that several seconds after the 80 knot speed cross check call had occurred, at a speed of about 110 KIAS, they had heard the light aircraft say he had missed his turn off and the First Officer had then seen a white aircraft tail light to the right of the centreline ahead and immediately called “Abort, Abort”. Their aircraft had been steered to the left with maximum braking and they had subsequently passed to the left of the Cessna with an estimated 3 metre clearance at a speed of approximately 40KIAS. Skid marks corresponding the account provided by CRJ crew were found beginning at a position about 670 metres after the point from which the take off had been commenced and extended along the left side of the 45 metre wide runway for 373 metres ending just beyond taxiway ‘B’ approximately 300 metres beyond the intersection of runways 06/24 and 13/31.

The controller on the TWR frequency was subordinate to the GND controller who was the designated “Controller in Charge” (CIC), a role for which the TWR controller was not qualified. He had been certified in the TWR position a month prior to the incident and the Investigation noted that only 49 minutes of his 81 hours training time for that certification were recorded as being at night.

He had been working without a headset and stated that he had “scanned the runway” before issuing the take off clearance to the CRJ and that “the runway had appeared to be clear”. He “did not recall actually seeing” the Cessna clear the runway but had subsequently seen the CRJ pass the Cessna, although he was not able to estimate their separation. He stated when asked what he had intended with his instruction to the Cessna to “turn immediately”, he responded that he had “wanted the aircraft to get off the runway even if it had to turn into the grass”

The NTSB formal determination of determined of Probable Cause of the event was as follows:

  • The failure of both tower controllers to maintain awareness of the position of (C2172) and ensure that the aircraft was clear of the runway before issuing a takeoff clearance to (the CRJ700).

The Final Report of the Investigation was adopted by the NTSB on 19 February 2009.

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