Recently, there was an incident involving a Lufthansa A350 flying to SFO which had to divert to OAK due to (at least what seems to me like) poor traffic management. In a nutshell, the approach controllers couldn't make room for an ILS landing; domestic traffic was landing using a visual approach, but Lufthansa's procedures demand ILS at night time.

This made me wonder to what extent long-term, but also instantaneous, traffic volumes are being considered when approving flight plans and (considering departure delays) issuing corresponding take-off clearances. Shouldn't somebody along the way have been aware of the IFR requirement and subsequently pushed back on either the flight plan or on issuing the departure clearance?

Even if this might have been an edge case, I'm now generally wondering to what extent international flight plans are coordinated and clearances granted "end-to-end". Do approach controllers know about all scheduled inbound flights and their instantaneous status (delays due to delayed departure, weather etc)? Can they delay intercontinental take-offs?

In Can airlines schedule more flight arrivals than the destination airport capacity?, this question is answered for domestic and intra-European flights, but I wasn't able to find any information on whether such mechanisms (CTOT, EDCT, ground delays etc.) also exist for long-haul traffic.

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    $\begingroup$ The "poor traffic management" in that case looks to be all & entirely within NorCal Approach, and very little that any sort of management upstream of that could have done to affect the outcome. The aircraft departed late, later than any flow control would be likely to direct (especially given good weather at the destination), so not like they could have finessed the timing to make things better. From all I read, it really looks like an arrival controller got obstructionist, and perhaps out of line... take a visual approach you're not allowed to accept, or else divert. Whoa, really??? $\endgroup$
    – Ralph J
    Commented Dec 20, 2023 at 4:07
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    $\begingroup$ Good point, I indeed mixed up flight rules and approaches here. I updated my question. $\endgroup$
    – lxgr
    Commented Dec 20, 2023 at 5:27
  • $\begingroup$ @RalphJ IIRC the approach controller offered the ILS approach as soon as a gap in the incoming flow of visual approaches would allow one and put the LH flight in a holding pattern. However, the LH flight did not have enough fuel to hold long enough and ended up diverting. $\endgroup$
    – Bianfable
    Commented Dec 20, 2023 at 8:38
  • $\begingroup$ It is certainly not the first time that a LH flight arrives at night in SFO, so it is hardly a surprise to NorCal approach that LH cannot accept the visual. Short distance flights that popup suddenly can be an unpleasant planning surprise, but with a flight time of more than 10 hours, NorCal approach can't really claim that they didn't see this one coming either. Sub par performance by the FAA on this one. $\endgroup$
    – DeltaLima
    Commented Dec 20, 2023 at 9:13
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    $\begingroup$ Totally off-topic, but the first few comments on the linked article were very civil and well written. Somewhat unusual for the internet in general. A nice find! $\endgroup$
    – FreeMan
    Commented Dec 20, 2023 at 16:50

2 Answers 2


To issue a departure delay to an aircraft you need to have reciprical arrangements with the country that it departs from. In the FAA they don't have that with all countries.

From my experience visiting the FAA Air Traffic Control System Command Center in 2018 they only had agreements with Canada and were looking at establishing with Mexico.

From my experience in Australia, we have many international arrivals into our large airports, and we have to set them up so international arrivals are considered in the sequence. We don't provide ground delays to long haul flights, there is too much variability to them and as was stated in the Lufthansa incident the aircraft departed late. This happens all the time with long haul flights.

Additionally, as the aircraft transits different airspace weather forecasts change, and level requests are not given at the time wanted due to traffic. This can both slow down and speed up an aircraft.

You have multiple airlines that will not accept a visual approach, especially the Asian and Middle Eastern carriers. When the aircraft is in the air, and you are getting regular updates on it passage through each FIR the destination system can be configured to see these aircraft coming.

In Australia we program our sequencing tools to automatically provide that spacing to that aircraft.

IMHO someone dropped the ball in the pre-planning of the sequence. Mainly the flow controller/s did not recognise the extra space required. But the justification for not vectoring 40-50 aircraft for the space for one due to safety is sound. Safety before efficiency.

This is a case of the requirements of the aircraft not being identified early enough to provide an efficient service.

To give you an example of this from Perth Australia and how we handle it Down Under. All aircraft that land internationally from the west of Perth are required to only be given a maximum of 5 minutes delay and half of them will not accept a visual approach during the day and even less at night. This is all fit into the sequence everyday with little issue, but none of them are included in the ground delay program. The ground delay program watches for their departures and updates the slots as they get closer. So, an aircraft that is late will free up restrictions earlier in the day and create more restrictions later in the day. This is then managed by the airlines as the trade slots in the program between aircraft.

  • $\begingroup$ Thank you, very interesting! So in other words, unlike for domestic flights, nobody explicitly tells inbound long-haul flights whether to (not) depart, and it's on the destination controllers to slot them in in real time? And regarding "seeing these aircraft coming", do controllers have visibility into the traffic flow of neighboring FIRs? $\endgroup$
    – lxgr
    Commented Mar 1 at 4:25
  • $\begingroup$ In Australia we know about all aircraft that are 90 minutes out from our airspace and then get updates every major event from them. If we have a surveillance sharing arrangement we can get accurate positions, but the procedural information is enough for us. We have no major airports within 45 minutes flight time of the FIR boundary outside of the Australian administered airspace. In the case of the Lufthansa incident that aircraft would have been known the FAA for a good hour plus before it arrived. $\endgroup$
    – Bullfrog
    Commented Mar 3 at 1:27

In Europe only flights departing from ATCFM area and some adjacent FIRs are subjected to slot allocation. The flights from airfields outside of these areas are considered as cleared and taken in account in flow planning using the estimated/revised time over the boundary of ATCFM area. Of course they will affect 'domestic' traffic but do take in account that major airports have airport slots for international flights. Also as a matter of trivia there is an option when declaring capacity at an airport to limit the flights by minimum RVR . For more info check CFMU manual and CFMU NOP enter image description here


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