As mentioned earlier about the occurring of fog , in this case the temperature and the dew point temperature are equal causing the thick fog . Amsterdam Schiphol Airport on an average day is taking care of 68 landing and departing flights an hour . When there are poor weather conditions the airport has some ‘’ special ’’ procedures . The most important thing we have to make sure of is safety . To ensure safety the airport has to take in to consideration that the distance between aircraft arriving and departing are greater than normal . The so-called “ low visibility procedures ” dictate that planes landing at an airport must be separated by six miles ( 9660m ), rather than the usual three ( 4830m ) The mass of electronic equipment in modern airliners makes it a simple process for pilots to land them in the dark , low cloud and equally , in the thickest of fog . But once on the runway , pilots rely heavily on the view from their plane windscreen to avoid collisions with an other aircraft or airport vehicles as they taxi to the stand . They need extra space when they are coming into approach and when they are taxiing around the airport . As u can imagine this has a major influence on the airports departure and arriving schedule . Departing aircrafts will be given a slot depending on the weather and airport capacity . Demand is managed by giving the aircraft a slot stating when it can take-off – the ‘ Calculated Time of Take Off ’ or CTOT . Normally , the aircraft should take-off within 15 minutes of the time stated in its flight plan but , if a slot is necessary , then this window is shrunk – to within five minutes before the CTOT or within ten minutes after the CTOT . If the aircraft can ’ t achieve this take-off time , then the pilot has to re-apply for a slot .

For example : The aircraft has a slot due to fog and should depart at 09:00Z . The CTOT given by EUROCONTROL is 10:14Z . Delay code 87 is active due to Airport limitations .