Description

On 11 October 2012, a Boeing 737-800 (EI-DLD) being operated by Ryanair on a scheduled passenger flight from Eindhoven to London Stansted did not follow its pre-take off taxi clearance and did not change to TWR when instructed. Without further communication, it then took off from runway 04 in day VMC without clearance. No actual loss of ground or airborne safety resulted.

Investigation

An Investigation was carried out by the Dutch Safety Board with reference to the aircraft Cockpit Voice Recorder (CVR) and the Voice Logging System in ATC. It was noted that the airport is a Royal Netherlands Air Force (RNAF) base regularly used by civil transport aircraft at which ATS is provided by RNAF controllers.

The 58 year-old aircraft Captain, who had been PF during the investigated event, had 19650 hours total flying time which included 5800 hours on type. The 45 year-old First Officer had 9500 hours total flying time which included 4000 hours on type. Both GND and TWR Controllers had been trained by the RNAF, qualifying 6 months prior to the event (TWR) and 2 years prior the event (GND).

The passenger apron is on the east side of the single runway 04/22 at the 22 threshold end and the only parallel taxiway if take offs are being made in the 04 direction is the west side parallel. At the time of this event, part of this parallel taxiway was closed for maintenance. As a result, GND cleared the aircraft to leave the passenger apron, cross runway 22 at its threshold and then initially follow the parallel taxiway until reaching the temporarily closed section, then continue onto the runway to backtrack until past it before leaving the runway at ‘F’ to rejoin the final bit of the parallel taxiway - see the aircraft route as cleared and as taken on the aerodrome diagram below.

The clearance onto the runway for taxi purposes was given by GND contrary to standard ATC procedures which require that TWR rather than GND control all access to an active runway. Once backtracking and approximately halfway down the runway, the crew requested and received their departure clearance. When the aircraft reached intersection ‘F’, where the crew should have turned right onto the last section of the parallel taxiway in order to approach the holding point at ‘G’ and await take off or line up clearance from TWR, the GND controller transmitted “this one to the right, and for departure contact TWR, 131,10, good flight”. The aircraft was then observed to carry out a 180° turn to the right on the runway and immediately begin and complete take off without clearance. The aircraft became airborne and no actual risk to safety occurred whilst the aircraft was on the runway or in the air.

The Investigation found that the CVR download disclosed some uncertainty about the intended take off in an exchange between the pilots which it was considered may have been prompted by the GND controller’s inclusion of the phrase ‘good flight’ so that when the Captain challenged the First Officer in an attempt to confirm that a takeoff clearance had been given, he responded, after some hesitation, with “we are cleared takeoff, yeah, it’s after airborne contact tower in the air, I think that was it” which was accepted by the Captain as stated.

It was noted that both crew members considered themselves well rested prior to beginning their duty that morning and that Ryanair had flights scheduled into Eindhoven several times each day. The Company airfield brief accessible to the crew contained selected AIPs information including the prohibition on 180° turns anywhere on the runway but they had not noticed this.

The failure of the GND controller to use certain elements of standard phraseology including “vacate” as the backtracking aircraft approached point ‘F’ was also noted.

It was confirmed that the work in progress which meant the taxiway section from ‘E’ to ‘F’ was going to be closed had commenced two weeks earlier and correct Notice To Airmen action had been taken. Details of it and the changes to normal taxi procedures were also being included in the Automatic Terminal Information Service (ATIS) broadcast.

The Conclusions of the Investigation were as follows:

• The intention of ATC was for the aircraft to backtrack the runway and vacate at intersection Foxtrot. In contrast to International Civil Aviation Organisation (ICAO) and European guidelines, permission for backtracking the active runway was given by Ground Control, not by Tower Control.
• The Ground Controller of Eindhoven ATC made use of non-standard RT phraseology for taxi and for instructions to vacate the runway.
• Limitations for airport use that are written down in the AIP were part of the pilots’ Company Brief for Eindhoven Airport, but were written in small print, and were therefore not very obvious. These limitations include the mandatory takeoff from the beginning of the runway by jet aircraft, and the restriction on 180 degree turns on runways and taxiways. During the Investigation the airfield brief for Eindhoven Airport was changed by the company, making the restrictions more obvious.
• The crew were aware of work in progress at the airfield but they were not aware of the content of the memo sent by Eindhoven Airport Authorities to all operators with the details about interim taxi procedures.
• Because the crew taxied in under TWR control after their earlier landing and were given clearance to backtrack the active runway, the crew were subconsciously under the impression they were under tower control.
• The use of non standard phraseology by ATC during taxi, led to some ambiguity, and was misinterpreted by the crew. The crew wrongly interpreted the departure clearance as a takeoff clearance.
• Despite expressing some uncertainty, the crew did not ask ATC for confirmation of a take off clearance.

It was also noted that since the only parallel taxiway at Eindhoven Airport is situated on the west side of the runway, 04 departures require that the active runway must be crossed upon leaving the apron which serves the civil passenger terminal. Taxiing traffic should, according to the rules, switch from GND to TWR for the crossing and then back to GND when instructed. Since such an arrangement would create extra workload and radio traffic for the crew and ATC, it was considered understandable that traffic crossing the active runway when taxiing routinely stay on the GND frequency. However, the Investigation considered that traffic crossing (or backtracking) the active runway should be under control of TWR in accordance with standard procedures - but no corresponding Safety Recommendation was made on this subject.

The Final Report was published in English translation on 11 July 2013.

Further Reading

• Non-Standard Phraseology
• Expectation of Clearance
• European Action Plan for Air Ground Communications Safety
• Cross-checking Process
• Complacency
• Crew Resource Management