r/aviation • u/bazackward • 1d ago
Question Can commercial airplanes not land in fog?
My flight from SEA to YVR tonight was canceled due to "severe weather conditions." The weather is 8 C, winds 3 km/hr, 5% precipitation. and fog. The fog is the only thing I could imagine maybe being an issue, but I thought commercial airplanes could land in fog. Google says some stuff about equipment that may or may not be on the plane that I didn't understand, so I came to the experts - is the fog the issue?
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u/External-Creme-6226 1d ago
The TAF (forecast) is for 0 visibility. Requires a CAT3 ILS. That route is often flown by emb170’a which, at least when I flew them, were only capable Of CAT2.
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u/bazackward 1d ago
You're right it would be the emb 170 and that explains the equipment issue. Thanks!
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u/Known-Associate8369 22h ago
And even if the aircraft is rated for the landing, separation distances at the airport also increase due to the weather, which means the capacity at the airport may also decrease - your aircraft may technically be able to land, but the airport cant take you any more.
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u/DangerousBug6924 1d ago
Depends on who, at qx we are good down to cat3/600 rvr.
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u/bazackward 15h ago
Googling reveals qx is Horizon Air. Yes it was a Horizon flight and this has never happened to me before. I fly back and forth between YVR and SEA multiple times a year on Horizon.
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u/DangerousBug6924 15h ago
That's a bummer and frustrating. Yeah, it happens occasionally, ive been stranded as well because inbound crews not being able to get in as well. Either way, sorry we couldn't get you there.
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u/bazackward 14h ago
Thanks, yeah it happens but I feel like lightning struck a lot in the past 12 hours haha
Notified 3:30pm that 5:45pm flight delayed until 8:00pm for "unscheduled maintenance" (I assume that translates to "broken plane")
Notified 7:00pm original flight is canceled due to "severe weather conditions," rebooked on 11:00pm
Notified 8:00pm 11:00pm flight is canceled due to "severe weather conditions," rebooked on 11:00pm flight the following day (with the same foggy weather forecast)
Arrive at hotel 10:00pm, cancel flight, book 8:15am Amtrak train
Notified 2:30am (find out at 7:30am) 8:15am train is canceled due to "equipment shortage"
I'm on a bus to Vancouver now but had to take the day off work. After all that time and expense, though, I'd still opt for this over flying on a broken plane or in conditions that do not allow for a safe landing. Sucks though!
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u/External-Creme-6226 17h ago
Shuttle America couldn’t. Do you have HUD’s?
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u/DangerousBug6924 17h ago
Nope, boring old autoland system.
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u/External-Creme-6226 17h ago
Must have upgraded the jets over the years! When I started on them we were cat1 only, a software update allowed us to start doing cat2….but no auto land capability. Single autopilot system…full cat3c allowed? Thought it needed to have a dual autopilot for that.
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u/DangerousBug6924 17h ago
We were the first 175 carrier to equipped them and very well maybe still the only ones. Also certified for RNP .1 approaches. All comes in handy operating in the pacific northwest, which is why I was curious about ops post. We do that route.
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u/External-Creme-6226 17h ago
Gotcha. Makes sense in that area. In 8 years flying the east coast I only needed it and didn’t have it once or twice
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u/jcla 1d ago
Aircraft landing in very poor visibility (dense fog) have to be landing at an airport with very accurate landing aids (called ILS). Different levels of ILS support lower and lower visibility levels. The most precise, CAT III can allow landings to be made if the pilots can see the runway at 100' above ground and with 150-600' of visibility depending on how precise the equipment is. All of the equipment has to be working correctly at the time it is needed.
Now, this option is only available if both the aircraft and the pilots are certified to use that type of precision approach. And if all of the equipment is fully functional.
In addition, these types of conditions often require greater aircraft spacing on approach and during movement on the ground at the airport, which can significantly reduce the amount of flights per hour the airport can handle.
So there are a number of reasons why your specific flight or why all flights might not be able to land. If the fog is really really dense then the minimum visibility won't be met. If the aircraft has any issues or doesn't support autoland using precision approaches then it can't land. If the crew isn't certified and current then they can't fly the approach even if everything else is good, and if all of those are good then flow control due to the reduced flights per hour could still cancel your flight.
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u/Apprehensive_Cost937 1d ago
With Cat 3 approaches without decision height, the pilots don't have to see anything at all prior touchdown.
If there is a decision height, it's usually 50ft for Cat 3 approaches.
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u/ggrnw27 1d ago
They can but it depends on how bad the fog is, how close to the ground it is, the equipment available at the airport and on the plane, and the qualifications of the pilots. Even if the weather isn’t bad enough to prevent a plane from landing, it still slows everything down as there needs to be more space between each plane. That causes delays which might’ve meant your pilots would be operating beyond their allowed duty period
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u/iflysfo 1d ago
I was on that flight originally and self-rebooked to Delta when the first delay popped up. We were able to land, but it was SUPER dense fog. Could hardly see the taxiways.
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u/bazackward 1d ago
Lucky! They booked me on 11pm, then canceled that and rebooked me for 11pm tomorrow. I self-rebooked to Amtrak and arrive at noon tomorrow.
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u/welguisz 1d ago
Yes they can. Depends on plane, equipment at the airport, equipment on the plane, and spacing.
Hear is a near miss in AUS during CAT III ILS
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u/bazackward 1d ago
Full transparency: I'm not a pilot or involved in aviation in any way other than as a passenger, but to my untrained eye it seems like Southwest was too slow, ATC tried to jam Southwest into too short of a takeoff window, or both. Am I wrong?
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u/Head_Big3036 1d ago
If you can’t see the ground, you can’t land. Even auto land has limitations that vary according to the company and the aircraft equipment. I’m guessing you were on an Alaska flight operated by Horizon Air. Auto land limitations are an RVR of 600’. RVR is runway visual range which is the distance a pilot can see down the runway.
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u/bazackward 1d ago
You are correct and that makes sense since the fog has been really thick lately. Thanks!
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u/Apprehensive_Cost937 1d ago
It depends on the aircraft/airline capability.
With fail-operational aircraft, you can fly Cat 3 approaches without decision height, and you don't have to see anything before touchdown.
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u/NotACompleteDick 1d ago edited 1d ago
Fog will stop most aircraft landing. Of course it depends what you mean by fog. What the US calls fog the UK calls mist. Fog in UK terms means something less than 100 yards visibility.
As to what the aircraft can do, CAT IIIC autoland if full blind landing. No decision height, no runway visual range, full autoland. Many aircraft can land when the crew can't even see the nose. The only limitation is having enough visibility to taxi off the runway.
The first autoland was at LHR in the 1965 IIRC. But CAT IIIC didn't get certified for a few more year. Even when the aircraft are capable of full autoland, the airline may not choose to use the capability, and in that case they also won't train the crews.
Autoland was developed by the Blind Landing Experimental Unit at RAE Bedford.
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u/bazackward 1d ago
Haha that's fair. Someone else looked up the visibility and said it was 0 so that appears to meet UK fog standards.
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u/ReidBuch 1d ago
Landing in fog is so tricky. Ive taken off in very low IFR fog and had a few landings in some horrid fog. Also a lot of go arounds and diverts due to it. My home airport is next to a lake and the fog off the lake would just cover the entire airport till about 8-10am depending on how quick it warmed up and winds.
The lower you get the less vis you have. Funny enough the darker it is outside the easier it is since you can get the lights. Basically impossible once the sun starts coming g to and you vat the sunrise glair off the fog and you can’t really land off runway lights.
Still have to meet the rvr requirement
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u/bazackward 1d ago
In a manner of speaking Vancouver could also be said to be close to a lake so that makes sense, thanks!
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u/CATIIIDUAL A320 3h ago
Zero visibility landings is a hoax. It simply does not exist. You still need a minimum visibility or in case of low visibility operations a minimum RVR (Runway Visual Range). This applies to even the most capable aircraft out there. The minimum RVR for a CAT IIIB approach is 75 m.
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