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Comment by kzrdude | Hacker News Reader

ATC can tell pilots what they need to know, right?

Its a flight planning mystery.

Lets say you are not flying to, but flying by, my hometown airport. You decide arbitrarily to use it as a divert in case of awful weather or engine trouble enroute or you just want a bathroom break (this is more of a Cessna 172 airport than a 747 airport)

I found a cached list of nine current NOTAMs for my home airport. Because its always better to overinform than to underinform, until the system overloads and crashes:

A long ramble that boils down to you can't use one of the IFR plates for a helicopter approach because of (its a very long story but relates to the crane mentioned below)

The modulation level on the closest VOR for identification/verification is low, although in legal tolerance, so you can use it but please stop trying to open the equivalent of a trouble ticket. We know the volume is both technically legal although low and not "turned up all the way". The techs say its safe until new parts arrive.

There's three failed tower lights in the area (three? Supply chain problems? Labor problems? WTF?) and one temporary crane obstruction. The crane is flagged and lit, and could theoretically be 60 ft AGL which is normally below the legal limit but its on airport grounds 0.13 miles away from one runway off to the side, so please try not to hit it. Also please don't bother reporting a crane off to the side of the approach; we know all about it...

Clearance delivery for the "big city" airport nearby has a remote trans/rec site nearby that's broken. Legal coverage is adequate (kind of a RAID array of retrans sites) so please stop reporting the reduced signal strength, we already know.

There's some kind of flood on runway 10 when it very heavily rains; the groundskeepers will fix the drainage problem; the NWS reports 0% chance of rain today so it probably won't be an issue, but don't act all surprised. This is not a NOTAM for groundskeeper work, that would be a separate new NOTAM.

Nailed it exactly. Also be advised that birds are in the vicinity of the airport.

One of our local muni airports adjacent woods always has a NOTAM advising of potential for deer on the runway.

Be advised somebody is mowing the grass near the baggage terminal.

Is someone who is planning multiple divert airports seriously expected to retain all of that information and recall it in the case of an emergency?

Seems like 10% of that info might be kinda useful to know and 90% of it is “BY FLYING IN OUR DIRECTION YOU AGREED TO ACCEPT …”

Not retain it, you probably have a copy with you which you would read if you did end up diverting somewhere. NOTAMs also affect which airports go in your "would divert to" list when you're planning the flight. E.g. if the NOTAMs say AirportA's lights are unserviceable, you wouldn't plan it as a diversion airport for your night flight.

Seems to me like “I am in a sudden aircraft emergency” is not the best time for a pilot to begin reading dry material.

There are many reasons to divert, not all of them big emergencies. Weather at your destination is worse than forecast, for example.

You're expected to have the information with you. Having read it before flight also increase the chance that it jogs your memory; "closest airport is CVG, didn't I see something... ah, yes, nuked last week, let's go to Columbus".

If I were a helicopter in IFR conditions and I just need a gas stop, I've never landed here, I'd forget about it, there's five heliports within 20 miles that have absolute zero drama. Legally technically the heliport is open but why risk it?

If I were shooting an IFR approach for currency in perfectly clear air, or with an instructor and its midday and cloudless right now, sure, have some good training.

If the engine's on fire, well, your odds are vastly better trying to land than trying to fly 20 miles away. If you're 600 feet off course and below 60 feet AGL you're probably going to crash anyway so don't worry about a crane.

They just have a crane onsite fixing some things, its not like the airport is closed just don't be surprised seeing some extra flashing lights and flags.

> Is someone who is planning multiple divert airports seriously expected to retain all of that information and recall it in the case of an emergency?

I am a pilot and yes, you are absolutely expected to be aware of all NOTAMS relevant to your flight.

FAA examiners will make you do it on checkrides, and depending on how cute they are feeling that day, they may very well quiz you, and will gleefully fail you because you weren't aware that, say, one particular runway was out of service, or there was a runway light out somewhere.

The implication is that someone planning a long cross country trip may have dozens of NOTAMS at many diversion airports to review. At some point all the NOTAM lawyering seems a bit much.

The NOTAMs for a commercial flight from JFK to LAX, for example, would be several pages long. Warnings about construction work at either airport, closed taxiways, cranes in the vicinity of the airport, enroute navigational aids which are unusable, etc. ATC can't relay that for every departing flight. Additionally, the NOTAM system is where they'd retrieve these from, so if that's down they have nothing to relay.

NOTAM notices are not only for planes but for other people and equipment using airspace, like drones, skydivers, ... Those are not always connected with ATC, but need the information from NOTAM to plan their activities

The question is, how will ATC know? I'm not that familiar with their systems, but maybe they rely on them to get critical information?

ATC will be fine to get everyone on the ground safely. There are procedures for everything including ATC itself being down.

I never doubted that. The question is if they could've worked without a ground stop by having ATC give them all info.

No. ATC gets busy enough as is, each plane needs NOTAMs covering their entire route, and if the system is down ATC isn’t getting them either anyways.

If I print the NOTAMs for a 600nm flight, they're going to typically go 4+ pages of NOTAMs that are fairly specific to my flight (just for departure, along route, and destination airports) and 15+ pages if I print all available NOTAMs in a fairly small font.

ATC can get them back down, but no new flights should start.

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