Closing down a runway at Dublin Airport that is used to deal with problem wind conditions could cost airlines and passengers up to €48 million a year, according to an official report.
The Commission for Aviation Regulation was asked by the Department of Transport to look at the impact of closing the airport's "crosswind runway" and whether climate change would have an impact on its use.
The report also examined how other major international airports managed without such a runway and if there were particular weather conditions in Dublin that made it essential. It found that closure could lead to between 1,468 and 2,251 flights not being able to operate annually – accounting for between 0.5 and 0.8 per cent of flights in a sample schedule used.
The report said taking into account flight diversions for airlines and the direct cost to passengers in lost time, the annual costs would be between €29 million and €48 million.
It also looked at whether climate change was playing a role in prevailing wind conditions at the airport. They have historically been in a west-southwest direction. However, it said there did not appear to have been a major shift in these conditions since 1988.
The report said the more likely future scenario – based on official government climate change projections – was for an overall decrease in wind speeds, but more extreme wind speed events in winter.
It said airports in Europe that operated without a crosswind runway had a couple of key advantages when compared to Dublin. Airports including Heathrow, Munich, Manchester, and Oslo all operated without one, but the report said they would "caution against drawing conclusions" with other cities.
The report said: “We find two factors that distinguish these airports from Dublin: the main runway headings are better aligned with the prevailing wind [direction and] the prevailing wind is generally more consistent.”
Safety
Aircraft generally land or take off directly into the headwind, the report said. When a crosswind is strong, there can be a “significant safety issue”. Under current arrangements, the crosswind runway comes into operation when “the crosswind component exceeds 20 knots on [the main runways]”.
It was also used when other runways were undergoing maintenance and to cater for "dual departures", especially during the normally business morning peak.
The report said there had been discussions previously over decommissioning the runway to allow for redevelopment of the airport. However, it concluded that, “in the absence of a clear business case demonstrating that the benefits of decommissioning the crosswind runway outweigh the costs, it must be retained as an operational runway”.
The report also looked at the length of problem wind events over the past two decades, saying the majority of them were fairly short. It said if a wind event was “say one hour”, the airport was generally able to recover operations on the day with “isolated disruption”.
However, if it continued for any longer than that, long delays, cancellations, and other knock-on effects were all possible.
A detailed look at records since 2000 showed that 2015 had the highest number of hours when at least one aircraft could not land on the main runway due to wind conditions.