Wow thats a nice topic...
Reasons, as being said...
Equipment
- On the ground
- degration of ILS/VOR/etc
- Degration while no FLOW CONTROL was installed... (there you have it "bookworm")
- unexpected event
- Crash
- aborted take Off (runway inspection etc)
- Blocked frequency on the tower
- Tower in reduced mode due to
- electrical failure
- ONLAN failure (read no more RADAR)
- fire
- etc...
- Lack of personel
All of those points can be seen as a reason of delay... It's ofcourse depending if any flow control was installed or not... If not then Sh*$t hits the fan...
- In the Air
- Aircraft in distress/emergency taking priority
- METEO
- Visibility
- Winds
- Ceiling
- Other...
- RVR below required RVR due to sudden deterioration of Wx
- etc...
- Aircraft performing a go around can cause delay, not only to himself but to others inbound to the field.
- Blocked frequency/RCF etc
- Aircraft reducing while being told to keep a certain speed. (This can cause a big gap in front of him and a pile-up behind him)
- RADAR
- Late handover by previous sector causing the sequence going wrong (a/c too late to descend ==> holding)
- Wrong vectoring...
- Loss of a safetynet / RADAR increasing the interval between a/c
In general the idea of flow is to keep us controllers working with a constant flow ( maximum traffic without holding), but any one of the abovementioned parameters will influence this and can cause tremendous delays...
If you want more ... just tell me
