Noise impact needs more rigorous assessment in phase 2 of Heathrow ‘operational freedoms’ trial

21st May, 2012

One of the recommendations of the South East Airports Taskforce (in which AEF took part) was that BAA should test whether both flight delays and the numbers of flights pushed into the night period could be reduced by allowing some flexibility to current rules on how the runways are used.  

Normally, one runway is designated for arrivals and one for departures, with the departure runway alternating at 3pm to allow residents some respite from the noise. Phase one of the ‘operational freedoms’  trial allowed aircraft arrivals (or departures) to use both runways simultaneously in response to specified triggers, such as an anticipated arrival or departure delay of ten minutes or more.

The annual number of flights at the airport remained capped at 480000, and no increases were permitted in either the number of scheduled night movements or the hourly scheduled capacity at the airport. Both BAA (with auditing from Cambridge University) and the CAA have now published their analyses of the first phase of trial, and the Aviation Minister this week announced the terms for phase two.

Phase one of the trial largely inconclusive

Overall, the CAA noted that for most of BAA’s identified ‘key performance indicators’ it was impossible to draw any conclusions from phase one of the trial, due to the “initial lack of an experimental design” and the fact that variables had not been tested in combination.

While the number of departures after 2300 was reduced during the trial, the data collected was insufficient to demonstrate a causal link between the operational freedoms and this reduction in night flights. Meanwhile, the average number of ‘respite hours’ (defined as an hour between 0700 and 2300 with no de-alternated westerly arrivals) fell from 9.5 in the baseline period to 5.7 during the trial period, according to CAA analysis. There were also some surprise results: stackholding (where aircraft circle waiting to land) on westerly operations has worsened during the trial, while easterly operations – expected to remain unchanged in the trial period – actually improved.

The research indicated a low level of awareness of the trial among nearby residents, yet complaints about noise rose two or three times, CAA reports. Whether this was due to the reduction in the length of noise respite periods, the lack of noise predictability, or some other factor is not apparent. The CAA identified significant problems in the ‘community engagement’ undertaken by BAA during the trial, hampered to some extent by the considerable lack of trust in the operator among the local community.

BAA had claimed that the results of the trial indicate that long term adoption of these operational freedoms would bring benefits to airlines (in fuel and direct costs) and to passengers (value of time) of £15m and £20m per year respectively, though the CAA dismissed such figures stating simply that any “benefit due to trial cannot be stated with confidence”. No estimate was made of economic cost or benefits to local communities.

Better assessment needed in phase two

AEF strongly supports the CAA’s recommendations that in the second phase of the trial a better methodology should be adopted. We believe that this needs to include measures to capture more accurately whether operational freedoms are effective in reducing numbers of night flights and, if so, whether or not this is an acceptable trade-off for those losing predictability in noise exposure and experiencing reduced respite periods.

The ministerial statement this week indicated that phase two of the trial will introduce several additional freedoms, including permission for aircraft scheduled to arrive after 0600 to land between 0530 and 0600 provided that the same number of flights scheduled to arrive between 0430 and 0500 are rescheduled to after 0500, and permission for some aircraft to be ‘vectored’ differently, taking off in a different direction from usual, possibly outside the ‘noise preferential routes’ (determined so as to minimise the number of people exposed to noise.)  In this context it will be particularly important to devise much more robust means of determining the noise impact of the trial on local communities.