AIRCRAFT OVERFLYING MENSTON
REPORT ON DISCUSSIONS WITH MANAGEMENT OF LEEDS/BRADFORD AIRPORT, on 26 May and at the Consultative Committee on 11 June 2015.
Report by Alan Elsegood, Airport Consultative Committee Rep., for Menston
An initial meeting was held to clarify the circumstances under which flights had been departing from Runway 32 and deviating from the Noise Preferential Routing (NPR). This had been occurring with effect from 30 April 2015. The purpose of this meeting (on 26 May) was to explain why and how the situation had arisen, what steps were being taken to address it and additional steps to prevent recurrence.
On 30 April 2015 all airlines flying out of LBIA had been subject to an update of the flight parameters. This is a regular occurrence both to compensate for the movement of the earth on its axis and to record changes in airspace regulations. Different airlines and different aircraft required the update in a different manner: there are three providers of this information which come by way of a computer program, to be downloaded onto the aircraft Flight Management Systems (FMS). One of the providers had apparently made an error in the programming, causing aircraft to fly past instead of over a specific market point on the flight path. Insofar as the computerised FMS systems on board the aircraft had responded to this programming, a majority of flights had subsequently deviated from the regulated Noise Preferential Routing (NPR).
The three companies are Honeywell, Navtech and Jeppeson’s: effectively international agencies which convert navigational data into computer programs which are subsequently used to update on-board flight management systems. The airlines receive these programs either on a data disk or a USB flash drive or, in the case of the most modern aircraft types, the data can be downloaded from an Internet browser. The updating can only be done when the aircraft are on the ground, not when they are in flight, and the latest update had been implemented on 30 April 2015. It was from this point that the deviations from the NPR started.
Investigation of the circumstances revealed that certain aircraft and certain airlines had remained compliant with the NPR. Where the airlines were compliant, it emerged that they had received their FMS navigational updates from either Honeywell (aircraft of FlyBe and the Boeing 757s operated by Jet2) or Jeppeson’s (British Airways and KLM). The compliant aircraft types included the Boeing 757s operated by Jet2 yet the Boeing 737s operated by the same airline had not been compliant owing primarily to the fact that the navigational update had been provided by the other organisation, Navtech. Navtech had also supplied the navigational updates to Ryanair and Monarch. Thus Jet2, Ryanair and Monarch, Thomson and TUI had a majority of non-compliant flights.
Understanding how the aircraft came to be off-track is complex, but it relates to the changes of compass heading required of each flight on leaving Runway 32 (which means the runway itself is pointed 320°) and departing to the North and West. Each jet flight must fly a specific route to follow the NPR unless there are safety or operational reasons for allowing a deviation. Turbo-prop engined aircraft are not regulated in this manner.
There are three significant navigational points relating to the track taken by aircraft departing LBIA via Runway 32. The first point is 0.5 nautical miles from the expected take-off point on the runway, by which time aircraft are expected to have achieved an elevation of 500 feet, such that they are permitted by Air Traffic Control to make a turn from 320°to 313°and to continue their climb to the next marker. The second marker is at 2.1 nautical miles (from the same starting point) and this is positioned on the farm to the north and west of the caravan park below the crest of Otley Chevin. Aircraft should have been instructed to overfly this point and set a track of 274°to keep them within the NPR. The aircraft would continue their climb, navigating at 274° until they overfly the third marker at 3.5 nautical miles, this way-point being positioned slightly to the north of Hag Farm Road, near Burley Woodhead. On overflying this third point, aircraft would be free to set their course to the ultimate destination along one of the ‘motorways in the sky’.
Because of the programming error, a majority of flights were missing one or more of these navigational points. So much for the manner in which the problem had arisen. Because the flight path was inconsistent as between aircraft and between airlines, the cause was not apparent to airport management, as the erroneous information was distributed by the methods previously indicated and not in text or narrative form. So it was not until the update had been installed in the aircraft FMS and the aircraft had commenced on the deviations from the NPR that the problem was observed. Once it had been observed and investigated, the question was how to achieve rectification.
Navtech, where the error was created, is not a client of LBIA but is contracted with by the individual airlines. Working with Jet2, LBIA management identified the error in the programming and requested Navtech to issue a revised programme. But NavTech, a Canadian company, was not ready to accept that they were responsible for the error, nor were they initially willing to re-write the programs at their own cost. The only way to implement the programme however, was for the airlines to receive a new data disk and to upload the information onto the FMS of individual aircraft when they returned to LBIA. This system necessarily applies not only to Jet2 but also to Ryanair and Monarch and some of their aircraft are not permanently stationed at LBIA. This explains why it has taken some weeks to identify, rectify and implement the solution.
However, there was a second factor at play, insofar as Navtech had wrongly identified the position of the first marker, and had relocated it in their program to the start of the runway. This meant that aircraft were being instructed to turn left much earlier, and this in turn meant they could not fly over the second marker-point.
As to the future, for approximately two years plans have been in preparation for a change in the NPR ex Runway 32, such that the revised NPR would follow a more north-westerly route along the A65 to approximately Ben Rhydding, followed by the turn either to right or left to take up the ultimate direction of departure to the aircraft’s destination. This proposal no longer has the approval of the LBIA management board as there are a series of potential conflicts in terms of applying this route, principally in terms of the risk of encroachment into military airspace or that airspace dedicated to Manchester Airport. This proposal has now been abandoned. The intention for the foreseeable future is to maintain the existing NPR, and the new Operations Director (Simon Whitby) affirms that all steps will be taken to ensure compliance with that NPR.
One method by which this may be achieved is likely to be by redesign of the waypoints previously noted. Subject to detailed discussions internally and then with the CAA, it is proposed to allow aircraft a greater distance after take-off to align themselves with the subsequent marker points, commencing perhaps by extending the marker at 0.5 nautical miles to 0.6 or 0.75 nautical miles. This extended distance on a bearing of 313°would allow aircraft to achieve a height in excess of 500 feet and bring them to a slightly more northerly position relative to the second marker at 2.1 nautical miles. From that point an aircraft would take up its heading of 274°which would make it more likely to make a turn within the confines of the existing NPR, and to stay within the swathe until leaving the NPR at 3.5 nautical miles. In relation to Menston, this would mean aircraft were less likely to turn early and/or to the south of the swathe and Menston residents would be troubled much less, if at all, by overflying aircraft.
Furthermore, the ground based waypoints are to be superseded by the introduction of satellite navigation directly importing to the FMS on board each aircraft. The estimated dateline for this change is winter 2017 – 2018, when the volume of traffic is low and a degree of experimentation can be applied. In effect therefore, once these changes are introduced, all aircraft which depart Runway 32 will be navigated by updated FMS Systems along a route which is marked by satellite signals and not by ground stations. Once the SatNav method has been implemented, all aircraft will fly along the centre-line of the swathe and any significant deviation to left or right of the centre-line will either be caused by wind, the weight of the aircraft or over-ride by the pilot. As regards the issues of wind and aircraft weight, the navigation system will compensate by adjusting the power and the controls to maintain a course along the centre-line, to the extent that it can be practicably achieved (within about 150 metres either side).
In the interim, I was assured that management at LBIA is completely determined that future flights will be on track and within the swathe of the current NPR and, further, that management has every intention of minimising noise intrusion for residents of Menston and other communities in the proximity of the airport. The Operations Director (who was previously at East Midlands Airport, and very much concerned with noise limitation) has offered to speak to the Menston Neighbourhood Forum at a date to be determined and to bring to that meeting the most up to date information available as regards compliance with the NPR, the levels of noise generated, proposals for any changes which might affect Menston and to listen to any representations made by or on behalf of Menston residents.
I was encouraged by the depth of investigation which had been undertaken, and the degree of transparency displayed at the meeting. I can accept that as the update was commissioned by the airlines, it was not a matter which LBIA had any control over, and that it resulted in a problem was not the airport’s fault. It is also quite clear that there was nothing obvious to indicate the source of the problem, and this has been a very steep learning curve for all parties, resulting in greater vigilance and a checking system for any future update to the FMS programs.
Representative for Menston on the Airport Consultative Committee