there's absolutely no room at all to park anything.
There are occasions when this will be so, and a common sense case-by-case diversion decision process allows the right decision to be reached at these times. But when an all-encompassing 'NO DIV' NOTAM is slapped on for days at a time there is no scope for using discretion. The stands are not full all day every day. And did you notice whether there was space available for additional executive traffic to park up at Landmark? A catch-all NOTAM excludes
everything by default. As mentioned earlier, at a time of high pressure, the ability to offload a couple of executive jets is immensely valuable to a busy ATC sector. A blip on the screen represents broadly similar workload whether it attaches to a Citation or an A380.
I don't understand how MAN's 'nodiv' NOTAM compromises safety? It doesn't at all.
Nobody has suggested that the NOTAM alone will result in a major incident. However, in commercial aviation both for aircraft operators and ATC, the overriding principle is to prevent the proverbial holes in the Swiss cheese from coming into alignment. The objective is to remove as many obstacles as possible which impede the safe operation of active flights. In a mass diversion scenario - which means many aircraft subject to the same adverse conditions simultaneously and several airports below acceptable minima simultaneously - the artificial (as opposed to enforced) non-availability of one of the largest airports in the system is a major thorn in the side.
Taking an example we have already seen once this Winter, consider a situation where the five major airports serving London have IRVR's around 100M at the same time. Many aircraft can land in these conditions but LVP's on the ground mean that arrival gaps must be substantially increased. This means that the holds quickly fill up, and the later aircraft reaching the stacks quickly calculate that fuel will become an issue before they get their turn to make an approach (which they actually could accept based on IRVR minima alone). These aircraft quickly fill up the spare capacity at airports such as Bournemouth and Norwich (presuming these are themselves still available).
As fog thickens in the Midlands and the North, LVP's come into force at other airports too. So the landing rates slow right down as arrival spacing is increased and the stacks gradually fill up. Aircraft can still land at BHX and EMA in our example scenario, but approach delays will build up as aircraft await their turn to make an approach with increased gaps. Some of these aircraft will then need to investigate other possible alternates. MAN is fully functional and within acceptable limits for our aircraft, but the airport has issued a 'NO DIVS' NOTAM and rules itself out. LPL, LBA and DSA now receive the modest number of diversions they can accept before declaring themselves full. But the aircraft keep on coming.
Now ATC and airline company ops are working flat out, not only working the regular traffic and the backlogged traffic, but also trying to secure arrangements with more distant airports to accept diversions. NCL say they can take a couple more, but their IRVR touchdown is now 250M and deteriorating. Some aircraft head for DUB, PIK and AMS. Flow control contributes to calming traffic flows, but the backlog of aircraft in the system still means high workload and the need to organise reroutes, plus increased coordination with adjacent sectors and units. There are no additional staff available to handle all this. The regular staff compliment must cope alone. MAN is at this point the only airport which has refused to accept diverted traffic. They again point to their NOTAM and say don't bother asking. What about a Dash 8 or an executive jet? No. Only if they declare an emergency.
You see, the NOTAM alone is not a safety hazard in itself. But one or several fuel emergencies are a safety hazard. And ATC sector overloads are a safety hazard. The 'NO DIV' NOTAM is arguably the biggest hole in the Swiss cheese. Remove it and the scenario above becomes significantly less likely. Reducing risk is what safety management is all about. When there are several aircraft holding simultaneously, there is one key wildcard factor to bear in mind. If the fifth aircraft in the queue declares a fuel emergency, other pilots can think: "B****r! We're going to get pushed to the back of the queue here! He was behind us! We'd better declare as well!" ATC can then face a domino effect with multiple aircraft declaring in rapid succession. This is when the real problems kick in. Somebody has to land last. Do you want it to be the one your wife and kids are flying on? Welcome to 'squeaky bum time.' And YES, I am aware of an actual scenario in which FIVE fuel emergencies were declared in a cascade effect of the type described. Obviously, I will not be posting specifics on that one.
The NOTAM is taken into account during flight planning, as is the additional fuel required for the 'new' altn airport if required
If there is only one adversely affected aircraft in the system that works a treat. But when all aircraft are affected and several airports are unavailable simultaneously (which does happen) neat plans drawn up in an office hours before go out the window. Alternates go below limits too during widespread adverse weather conditions. Remember, ATC loading has to be accounted for as well as the contingency for each one flight considered in isolation.
It's absolutely no different than MAN RVR's being below limits in periods of bad visibility,
By the law of averages, there are times when MAN itself is one of the worst affected airports. When that happens other adjacent airports do step up to the plate and 'go the extra mile' to help out. It would be
so, so helpful to ATC and airlines alike if MAN would do it's part for the common cause when the converse is the case. If they can only accept a maximum of five aircraft, fair enough. Accept those five. Every little helps! Nobody is demanding a free-for-all, but please pitch in and do your bit to help out
as every other UK airport of size already does.
aircraft from neighbouring airports don't suddenly dropping out of the sky because they can't make MAN.
Invoking sensationalised imagery in this manner is most unhelpful to what is actually a very serious safety debate. The reader is invited to identify this as the scenario under discussion, laugh out loud, and then dismiss the entire debate ... ergo, there isn't really a problem. Safety planning doesn't work like that. Hollywood disaster-movie imagery does not contribute to constructive consideration of the real-world issues here. ATC sector overloads can and do happen from time to time despite all measures taken to avoid them. Aircraft do declare fuel emergencies from time to time despite all best efforts to avoid these. And multiple 'cascade' declarations of fuel emergencies can happen too (for the reasons outlined above). It is incumbent on a safety-led system to defuse factors which could significantly contribute to such incidents arising in the first place. From that perspective, consigning the blunt-instrument 'NO DIVS' NOTAM culture into the dustbin of history would be the single most helpful step forward I can think of at this point.
If the UK values its admirable safety record, then there is no room for complacency to take root. Efforts to keep those holes in the Swiss cheese from coming into alignment must be unrelenting.