Greetings to all! My first post in this forum, but a question about "large aircraft at OKC" recently sparked this rabbit-hole of a topic, and I believe it belongs here.

It is well established that all commercial flights submit a flight plan and choose an "official" alternate airport. In the case of large American airports, such as those along the east coast of the U.S., an alternate airport is usually a large one with FIS services available during most hours of the day. JFK & EWR have BOS, PHL, and IAD within nearby reach, and my guess would be that the official alternate would be one of these others.

But for the center of the U.S., such as DFW or DEN, there is no nearby mega-hub (leaving IAH out of it for this discussion, mainly due to this question being about weather diversions, and that which affects DFW usually can affect IAH as well). Therefore, an alternate airport would generally have to be something along the route, with FIS facilities available at the airport, even if only at limited times.

In the case of an LH A343 flying FRA-DFW, it was diverted to OKC, which may or may not have been listed as the official alternate.

So, my question is this: if OKC was listed as the official alternate for this international flight, what exactly goes on at OKC after the official notification? I've made a list of things that I think would have to happen, but I don't know for sure. Please help with this list:

* Flight plan is officially filed.
* This flight plan is placed into a computer system that notifies the FAA (?) as well as airports en-route.
* The alternate airport is notified, as is the FIS station.
* Some type of "stand-by" mode is in effect until the plane either arrives at the destination airport OR actually diverts to the alternate.

Thank you for the replies!!

OpsSpecs, approved in the AOC, specify approvedcalternates which are used normally and flight planned accordingly. Medical and emergencies are a bit different. The vast majority are operational 24/7/365 and no special standby status is employed. The mid-Pacific and Arctic alternates are on standby. Bradley (KBDL) is often host to NYC diverts, unplanned usually. I’ve seen foreign carriers parked on ramps, closed runway 01/19, APUs running waiting to go or receive Customs.

A BA B747 sat for hours one day, engine running, due to inop APU, waiting to head back to JFK when it opened. No FIS available, which is pretty frequently the case in my experience, probably stopped at KPSM or KBGR a dozen times for C&I when Bradley office was closed.

It may have changed, but when I flew ATC didn’t know your filed alternate. When the crew decides to divert, ATC issues a clearance to wherever the crew requests. Only “control” information was forwarded to ATC from the filed flight plan—times, departure and arrival airports, route, level, TAS or Mach, as required,

PSAatSAN4Ever wrote:

So, my question is this: if OKC was listed as the official alternate for this international flight, what exactly goes on at OKC after the official notification? I've made a list of things that I think would have to happen, but I don't know for sure. Please help with this list:

* Flight plan is officially filed.
* This flight plan is placed into a computer system that notifies the FAA (?) as well as airports en-route.
* The alternate airport is notified, as is the FIS station.
* Some type of "stand-by" mode is in effect until the plane either arrives at the destination airport OR actually diverts to the alternate.

Thank you for the replies!!

For where I work, and where I have worked in the past, there is no such thing as an "official alternate".

As part of the flight dispatch package, we have a list of suitable alternates. None of these airfields and no ats facilities en route will have advance knowledge of this. Sometimes these alternates are already part of the network which eases logistics should we divert and sometimes they are not. For a flight into Manchester, we may have East Mids and LHR airport as an alternate. En route we may use Cairo, Athens, Rome, Brussels etc. That doesn't mean we have to stick to the list. I wouldn't hesitate to use Birmingham or Stansted if needed

In the event of a divert, we notify ats of our intent and then our ops centre who try and facilitate ground support etc. Sometimes the other way round depending on the nature of the divert.

Some random points:

A filed alternate is not required. You can dispatch without one, but the dispatch requirements are different.

The point of filing an alternate is for planning and is part of generating a minimum fuel figure. If you fly without an alternate, for example with "Island Reserve", the weather requirements for your destination are stricter, and you probably need to carry more fuel.

A filed alternate is not, as such, your go-to operational option. Once in the air you continually reevaluate your options. For example, if you have an engine failure 1000nm from your destination, you'd most likely land somewhere other than your destination or alternate.

ETOPS/EDTO alternates are the same. They exist to make you legal to dispatch and may allow you to carry less fuel. You might overfly plenty of other airports en route, all options for a diversion.

To add, air traffic control, in the FAA at least, does not have any knowledge of a flight’s filed alternate. There can only be one clearance limit for an IFR aircraft and it it typically an airport where a full stop landing is expected to terminate the flight plan.

In the case of weather below an aircraft or air crew’s minimums, ATC may suggest alternates where the weather is reporting/ forecast better although this is more typically seen with GA aircraft.

Speaking from an American/FAA rules perspective: Depending on the weather and the specific type of operation a commercial flight may or may not be required to designate one or more alternate airports. In any case, neither the airport(s) nor ATC have any knowledge of which airports are designated as alternates and it is up to the crew to inform them of such if the need arises. Airlines often will designate an airport in their own network to simplify the logistics of ground handling, dealing with pax, etc. but this is not required. Another consideration for international flights would be the availability of customs/immigration although allowances are certainly made for true emergency situations.

As an example at my company when flying into EWR we typically use ACY as our alternate due to having plenty of space to park and low traffic congestion.

PSAatSAN4Ever wrote:

* Flight plan is officially filed.
* This flight plan is placed into a computer system that notifies the FAA (?) as well as airports en-route.
* The alternate airport is notified, as is the FIS station.
* Some type of "stand-by" mode is in effect until the plane either arrives at the destination airport OR actually diverts to the alternate.

PSAatSAN4Ever (Topic author),

Not sure I understand some of the items in your list. When you state, "This flight plan is placed into a computer system that notifies the FAA as well as airports en-route," which en-route airports would need to be notified of a filed alternate? In the example you cited, LH flight FRA-DFW, if the aircraft overflies Goose Bay, Cleveland, and St. Louis, for example, why would any of these stations require notification? And, when you state, "The alternate airport is notified," which airport agency would need notification that the airport has been filed as an alternate?

As you can tell from the above responses, I don't think it is as complex as you imagine. The alternate is filed to comply with applicable regulations and is for use by the crew. Many airlines will use an "on-line" station for ease of logistical issues. If an "off-line" station is required, as in your example, in many cases the airline will establish a contract with an entity at the selected airport--an airline that serves that airport, an FBO, or other handling organization, i.e., ATS, Menzies, etc., as appropriate, to handle the aircraft in the event of divert. Should it be necessary for the flight to divert, the crew notifies ATC of the desired destination, and the company--usually dispatch or operations control--will simply notify the contracted agency which will implement the contracted functions such as aircraft parking, fueling, FIS. Yes, there are quite a few items that must be completed in the event of a divert, but all the "pre-notifications" and "standby mode" you suggested are not required.

e38

An amusing story, I was flying Bangalore to Mumbai. The weather in Mumbai was very bad with torrential rain and low vis. We made two approaches and even with the HUD saw nothing. We announced our intent to go to our alt. which was Hyderabad and headed that way. When we landed the first thing ground control asked us was "Why are you here?" We were surprised and just said we diverted from Mumbai. It took 4 hours to get fuel and another flt. plan. We finally departed and made our way back to Mumbai as the rain had ended. It was a non event but then we still had to fly Mumbai-Dubai. When I got home after the flight I called operations I told them our horrible delay in Hyderabad. I told them if I were ever in that position again I would head straight back to Bangalore where we had a hub and never back to Hyderabad.

When the dispatcher or flight planner sends out the release/flight plan, the alternate(s) he selects get appended automatically to the ATC strip. Most controllers probably dont read it or notice but the alternate does get filed with ATC. In some instances, flight plans can be rejected by ATC because of unauthorized alternates. China does not accept flight plans for HKG with TPE or any other Taiwan airport. Usually, most airlines flight planning software auto-files after release gets sent so in that case a release gets sent out with an acceptable alternate, filing is inhibited and amended release sent out with the alternate the dispatcher wants.

Typically, dispatchers dont notify stations they are listing them as an alternate. Some exceptions to that are outstations late at night or stations with limited capacity to accept diversions. With a single dispatcher working 50-60 flights, it would be impractical and impossible for a dispatcher to call for every flight. Usually, the first notification a station gets is when the dispatcher calls to let them know they are going to be receiving a diverted flight.

There is something in the industry known as a “paper alternate”. The regulation requires an alternate and fuel to get to an alternate but the conditions at the destination are highly unlikely to require a diversion. Normally, this is the closest authorized airport depending on NOTAMs and other constraints.

Alternates change frequently in flight and before gate departure as conditions change. If a flight is overweight based on landing weight, fuel including the alternate can be moved around to allow for more fuel to be burned in order to accomodate more passengers and freight. If a flight is holding, change to a closer alternate can move fuel from alternate to hold and thus allow longer hold times. If the planned alternates become saturated with diversions or weather deteriorates, alternates can get changed to something more suitable to the current conditions.

Alternates can cost airlines a significant amount of money to maintain. ETOPS airports in particular. An airline might divert once every ten years to a place like CDB or GDX but regulations require ground handling in case of ETOPS diversions so airline needs to spend money on these kinds of contracts and equipment for the rare occasion they might be needed. Airports like BGR, YQX, YYT and SFJ are well positioned geographically for this and make good money from airlines that need options for enroute landings.

MSJYOP28Apilot wrote:

When the dispatcher or flight planner sends out the release/flight plan, the alternate(s) he selects get appended automatically to the ATC strip. Most controllers probably dont read it or notice but the alternate does get filed with ATC. In some instances, flight plans can be rejected by ATC because of unauthorized alternates. China does not accept flight plans for HKG with TPE or any other Taiwan airport. Usually, most airlines flight planning software auto-files after release gets sent so in that case a release gets sent out with an acceptable alternate, filing is inhibited and amended release sent out with the alternate the dispatcher wants.


----


Alternates can cost airlines a significant amount of money to maintain. ETOPS airports in particular. An airline might divert once every ten years to a place like CDB or GDX but regulations require ground handling in case of ETOPS diversions so airline needs to spend money on these kinds of contracts and equipment for the rare occasion they might be needed. Airports like BGR, YQX, YYT and SFJ are well positioned geographically for this and make good money from airlines that need options for enroute landings.

Once in flight, you can divert to Taiwan ports, but the diversion cannot be initiated from Mainland airspace. You can only initiate the diversion from the Hong Kong FIR.

EDTO/ETOPS alternate ground handling indeed, plus RFF (Rescue and Fire Fighting).

Thank you all for your responses! Dang, I learned a lot!

With regards to "alternate" airports, what I was looking for was the near-to-the-end-of-the-flight diversion airport, not necessarily all the en-route airports along the way that a plane might have to stop in. In other words, I'm not looking at the "disruptive trans-Atlantic passengers forces diversion to Bangor" story, more the "Lufthansa's DFW-bound flight was forced to divert because of weather".

But I got my answers - again, thanks to all!

atcdan wrote:

To add, air traffic control, in the FAA at least, does not have any knowledge of a flight’s filed alternate. There can only be one clearance limit for an IFR aircraft and it it typically an airport where a full stop landing is expected to terminate the flight plan.

Alternate airports are also not obligated to accept aircraft unless there is an Emergency.