B738, Manchester UK, 2003
B738, Manchester UK, 2003
On 16 July 2003, a Boeing 737-800, being operated by Excel Airlines on a passenger flight from Manchester to Kos began take off on Runway 06L without the flight crew being aware of work in progress at far end of the runway. The take off calculations, based on the full runway length resulted in the aircraft passing within 56 ft of a 14 ft high vehicle just after take off.
On 16 July 2003, a Boeing 737-800, being operated by Excel Airlines on a passenger flight from Manchester to Kos began take off on Runway 06L without the flight crew being aware of work in progress at far end of the runway. The take off calculations, based on the full runway length resulted in the aircraft passing within 56 ft of a 14 ft high vehicle just after take off. The event was not reported - by ATC - until a week later.
This is an extract from the aircraft serious incident Report (3/2006) published by the Aircraft Accident Investigation Branch (AAIB), UK:
[…]Runway 06L was in use but the flight crew were not aware that this runway was being operated at reduced length. This was due to work-in-progress to remove rubber deposits at the far end of the runway, which was out of sight from the 06L threshold end as the runway is built over a slight rise in the ground. Due to a difference in interpretation of information passed between Air Traffic Control (ATC) and the flight crew, the aircraft entered the runway from holding point AG, rather than the expected holding point A (Figure 1), and the takeoff was conducted using a reduced thrust setting calculated for the assumed normal runway length. As the aircraft passed the crest of the runway, the flight crew became aware of vehicles at its far end but, as they were now close to their rotation speed, they continued and carried out a normal takeoff. The aircraft passed within 56 ft of a 14 ft.
[The Captain] did not read the relevant NOTAMs, deciding instead to check them once he was on the aircraft. Whilst the flight crew had the intention of reading all the relevant NOTAMs before departure, they missed the opportunity to thoroughly brief together in the crew room. Once on the aircraft, they were subject to the usual distractions involved in pre-flight preparation and the pressure of trying to make their allocated departure time. As a result, despite their stated intentions, the NOTAM of critical importance to their departure, detailing the work‑in-progress on Runway 06L/24R, was never read. Although unaware of the content of this NOTAM, the Automatic Terminal Information Service (ATIS) provided both pilots with another opportunity to learn of the work-in-progress.
[…] The weather information from the ATIS was used by the pilots to calculate their performance for the takeoff. This was done, however, using performance figures for Runway 06L at its normal length and not the reduced length in force at the time of their planned departure.
[…]The [take-off] performance figures calculated were correct for the normal runway length and allowed for the reduced thrust takeoff which was subsequently performed. The pilots had no data available which would have allowed them to calculate their performance for the reduced runway length and they were not in a position to obtain this data at such short notice.
Subsequent calculation revealed that the crew correctly calculated their takeoff speeds based on their belief that they were using Runway 06L at its normal length. The aircraft was, however, more than nine tonnes overweight for a takeoff on the reduced length Runway 06L when using the calculated reduced thrust.
Further the Report specifies that the reason why the crew might have missed the significance of the takeoff run data available in the NOTAM and ATIS, and later on passed by ATC, was that they were both used to dealing with performance figures specified in company documents in feet.
[…] The use of metres, when specifying the runway distance available in the NOTAM and the ATIS broadcast, conformed to standard international practice. […] Hearing the distance in metres failed to raise the same question in their minds that might have occurred had they heard the figures in feet.
In the Conduct of the Flight section, the Report states:
[…] The co-pilot believed the work was in the threshold area of Runway 06L; this was reinforced by his mistaken belief that ATC were instructing them to line up at an entry point part way up the runway. The commander stated he believed the work was at the far end of the runway in an area outside that affecting their takeoff performance. Runway 06L/24R slopes up from both ends towards the middle creating a slight hill effect, sufficient for the crews of B737 sized aircraft to be unable to see beyond the highest point until they are some way down the runway. Thus, the vehicles on the runway were not visible to the crew as they lined up, denying them a final opportunity to become aware of the actual situation concerning the work-in-progress.
[The] initial taxi clearance from ATC did not specify the clearance limit, stating only that they were cleared to the “holding points” for Runway 06L. At that time, there was no requirement to specify a clearance limit; this is now a requirement and has been incorporated in to MATS [UK Manual of Air Traffic Services] Part 1. As a result of the original clearance, when ATC had asked if they could accept a departure off “THE REDUCED RUN AVAILABLE ON RUNWAY 06L” followed by the crew’s reply of “YEAH FROM ALPHA GOLF”, it is likely that the omission of the clearance limit meant that ATC believed the aircraft would be taxiing for holding point A1, whilst the crew believed they were expected to taxi to holding point AG.
On handover to the tower controller, the clearance was ambiguous in that the crew were merely cleared to “LINE UP AND WAIT ZERO SIX LEFT”. The tone of the co-pilot’s reply of “WE’RE TAKING IT FROM ALPHA GOLF” indicated that the crew had some doubts as to their runway entry point clearance, but this response was interpreted by the controller as a statement of intent rather than a question. However, it seems apparent that ATC were also concerned, as the flight crew seemed prepared to commit to a takeoff on a reduced length runway, but effectively made shorter by entering at holding point AG. As a result, when ATC replied with….”IF YOU’RE HAPPY WITH THAT THAT GIVES YOU ER SIXTEEN SEVENTY METRES” the crew were provided with another opportunity to become aware of the reduced takeoff run on Runway 06L. This information, which applied to a takeoff on the reduced length runway from holding point AG, was either missed by the crew or the ambiguity of the exchanges led them to mis‑interpret this as the takeoff distance available from holding point AG at the normal runway length. […]
The Report identifies the following Causal factors leading to the serious incident:
The crew […] did not realise that Runway 06L was operating at reduced length due to work-in-progress at its far end, until their aircraft had accelerated to a speed approaching the rotate speed (VR), despite:
- Being in possession of a NOTAM concerning the work-in-progress
- The ATIS broadcast relating to the work-in-progress
- ATC passing information on the takeoff distance available
At this point, the aircraft was approaching seven vehicles on the runway and was at a position which precluded an abort within the useable runway length remaining.
[…] The subsequent investigation revealed further incidents had occurred during the course of the work, the most significant being on the night of 15 July 2003. On this occasion ATC had instructed three commercial passenger aircraft to go-around after they had knowingly positioned them to land on the reduced length runway. The crews of all three aircraft were unaware of the reduced length available and, when informed, stated that it was insufficient for them to be able to land. The closest of the aircraft, a Tristar, was at a range of 2.5 nm when instructed to go-around.
The UK AAIB Report of the Investigation includes six Safety Recommendations in respect of matters highlighted by the Investigation and not fully resolved at the time of publication.