Diverting to Alternate!
Diverting to Alternate!
Sometimes, Flights Don't Go as Planned...
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Diverting to Alternate!
For my birthday, Bunny surprised me with tickets to a delightful new play called, “Come From Away.”
Have you heard of it?
It’s a musical about the multiple 9/11 airline diversions to the tiny town of Gander, Newfoundland, Canada, after US airspace was shut down.
The normally quiet, remote hamlet was overwhelmed with international heavies, loaded with more passengers than the entire town’s population!
Well, the play got me to thinking: We haven’t ever really discussed here on the blog what happens when you can’t make it to your destination…
Diverting to Alternate!
Diverse Diversion Dealings
An airplane flying from Point A to Point B may have to “divert to an alternate” (Point C) for any number of reasons. Here’s just a few:
- Bad weather at the destination;
- Mechanical issue;
- Passenger misbehavior requiring police intervention;
- Passenger or crew medical issue, and, (rare):
- Airspace shut down due to a national emergency.
The most common reason for a diversion is your destination weather going down.
While most modern airliners can land in near-zero visibility conditions, other factors may contribute as well, such as thunderstorms over the field, strong crosswinds, severe icing, snow plowing unable to keep runways clear in blizzards, etc.
Diverting to Alternate!
Fuel Planning
Most often, a flight is planned with these possibilities in mind, based on the actual forecast.
Typically, an airline flight plans fuel for:
- Enroute fuel to destination;
- May include extra fuel for anticipated delays, deviations around enroute weather, and altitude changes for ride (turbulence)
- 45′ extra fuel (that’s minutes, not feet!—domestic FAA requirement), or:
- 30′ extra for International;
- Plus 10% extra (with some mods);
- Anticipated holding pattern fuel;
- Fuel from the destination’s Final Approach Fix (FAF) to alternate;
- When the alternate airport weather is iffy, a second alternate may be required; in that case fuel to the farthest of the two alternates;
- Additional fuel at the discretion of the Dispatcher (Flight Planner);
- Added fuel at the discretion of the Captain.
While I was flying domestic on the Airbus, after consulting with my FO, I would only need to add fuel maybe 1 out of 10 flights; over on the international side of things, I almost never need to add.
Dispatchers are pretty sharp!
Caveat: Why not just take full fuel all the time?
Keep in mind that, for any given airplane or flight, the more fuel you carry, the more fuel you burn—and the less payload (passengers and cargo) you can carry.
Yep, everything on an airplane is a compromise!
You're the Captain: Medical Emergency!
“Captain, we’ve got a passenger losing consciousness.”
What do you do, Captain? You’re in charge of an airliner; you’ve got limited time, imperfect information, and you must make sound decisions, all while hurtling through the air at nearly 10 miles a minute!
Just one of many true tales in…
There I Wuz! Adventures From 3 Decades in the Sky Volume 2!
Diverting to Alternate!
The Missed Approach
As mentioned above, the most common reason for diverting is being unable to land due to bad weather at the intended destination.
This often comes in the form of a “Missed Approach.” The plane flies down the ILS (Instrument Landing System) for a given runway, to the “Decision Height” (DH)—often around 200′ above the runway elevation.
At the DH, if the runway is not in sight, and the plane must “go around.” That is, cobb the power and climb back up. During an instrument approach, this is called a “Missed Approach,” and there will be a specific path the airplane must fly, which will take it to a Holding Pattern.
At this point, the flight crew must decide whether to wait out the weather in a holding pattern, try another approach, or simply divert to the alternate airport, and wait out the weather on the ground there.
Take a look at this amazing GIF, above.
Aircraft arriving into the ATL terminal area find themselves confronted with building thunderstorms. Most go into a holding pattern to wait it out, but some, low on fuel, divert to their alternate!
Thirsty for more? READ ON!!!
Part 2: Diverting to Alternate!
Cap'n Aux Shares His Latest Diversion Tale!
Available NOW!
Direct Link: https://capnaux.com/diverting-to-alternate-part-2
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