Just one month after Lelystad airport was given its own air traffic control service, the Dutch safety board is to investigate five incidents in which aircraft were allowed to get too close together.

The air traffic control unit was brought in to prepare the airport for commercial flights using bigger planes. The airport is now primarily used by flying schools and small private aircraft.

Until recently, pilots would communicate with each other about take offs and landings, but that is now done via the control tower. The Dutch air traffic control organisation LVNL says it is introducing new measures from this weekend including single direction take-offs and landings.

Officials will also take steps to limit the amount of information which pilots are required to make public, such as when they start a motor. Pilots have been complaining there is so much chatter on the two frequencies at their disposal that they are missing vital information local broadcaster Omroep Flevoland said on Friday.