As the Unmanned Aircraft Bill goes before parliament for a second reading, the British Airline Pilots Association (BALPA) says new European research backs its concerns that the number of drone flights in controlled airspace is being underestimated.

The research by Eurocontrol involved comprehensive monitoring of airspace around the Latvian airport of Riga.

Latvian airspace has similar restrictions on drone operations to the UK and Riga has a similar number of movements to London Luton Airport with the same single-runway configuration.

In a 37 day period, the study recorded 171 drone flights, of which 159 (or 91%) were considered illegal because they broke national regulations such as height limits or rules regarding how close to an airport you can fly.

A total of 71 drone flights were detected closer than 5km to the runway during the monitoring period, and 75 were detected above 400ft.

BALPA’s flight safety department says these results are worrying and show that regulation alone is not enough. It notes that training, education and enforcement of drone laws is also vital, as is a means for drones to be electronically identifiable.

With this is mind, BALPA says the increased police enforcement powers contained in the proposed unmanned aircraft bill are welcome. The pilots union wants to see asimilar monitoring study here in the UK, to identify the actual presence of drones in the vicinity of a UK airport.

BALPA Flight Safety Specialist, Joji Waites, said: “Pilots have always feared that their reported sightings of drones are just the tip of the iceberg and this study backs that concern.