Originally Posted by
Musket90
I agree with DD, provided the CAT I hold position is at the runway end and not at an intermediate take-off position and the conditional line-up clearance is following another departure from the same point, except if both are departing from the same intermediate position. If an intermediate departure crosses the Cat I hold before a full length departure has passed then this I believe to be an incursion.
In addition to protecting the runway cleared and graded area, for precision approach runways CAT I holds are to protect interference to radio-aids, penetration of the Obstacle Free Zone and penetration of the OCA/H.
The CAT I hold only offers protection of the inbound approach from collision with a mobile obstacle. It does not protect the Clear and Graded, it does not protect the navaids. It does not necessarily protect the OCA/H for non precision approaches. It does not protect the departing aircraft from the inbound aircraft, so crash location risk assessments are required as well.
Can we clear this up for once and for all?
In addition, remember that if an aircraft is at a CAT I hold, you cannot necessarily taxi behind it without colliding with it.
Are you considering the aircraft at the CAT I hold as being the nose on the line, the nosewheel on the line, or you can see it over the nose of the cockpit? Which one to you consider to be corrrect?
Controller should only ever issue conditional line-up clearance after a full blown risk assessment. I would have to say that LHR and MAN runway 2 departure only cases should be fairly easy in this respect. However, remember you do get some landings on the "departure" runway at Heathrow, but procedures/tasks/alarms should manage this and no conditionals when arrivals are expected helps.
If you actually dig into the aerodrome standards books, such as Annex 14 and CAP 168 you will find that the whole subject is a bit of a mess.