"Arguendo:  Could wait 5 minutes to give an unknown comms-equipment-damaging phenomenon to potentially subside."

"Negative, if there's extraordinary circumstances not local to this airplane then land may have urgent instructions on emergency frequencies.  We can use the backup emergency radio if there's an ongoing damage source applying only to turned-on equipment."

He doesn't actually think aliens just wiped their satellite network... but there could be some other weird thing going on that's not local to the plane, sure.  He doesn't actually know what's supposed to cause simultaneous failure of all of those radio frequencies.  He reaches out to the shortwave radio switch, then pauses.  "Predict 2:1 that 14.3Mhz is unobstructed."

"I'm at 1:1.  Bet my 40 if it works vs your 60 if it fails."  It's not particularly about money or pride, in this case, it's about which of them is forming a better grasp of the general emergency.

"Ack."

He flips the switch that turns on the shortwave radio.

Shortwave radio cannot ultimately be reliable in the sense of 99.999% uptime.  Immediate, unannounced impacts of solar flares actually will knock it out.  So long as everything is working correctly, satellite communications are more reliable than shortwave.

What shortwave radio is, is simple.  Radio in the 3-30MHz range will bounce around between the ionosphere and the land, potentially for thousands of kilometers.  Shortwave does not require locking onto a satellite, nor frequency clocks that run at exactly 70.231 GHz.

You can, if you know what you're doing, build your own shortwave radio in a cave out of a box of scraps.

A shortwave radio in dath ilan is therefore built for exactly one purpose:  Exception handling.  A shortwave radio is a failover for when something less simple breaks.

And in dath ilan, when code crashes due to an unhandled exception inside an exception handler, the resulting code dump includes a standard message saying the programmer needs to be fired.  Shortwave radios are built to work very simply, for when somebody tries to use them during what's at least an exception and possibly some sort of very distracting emergency.

Shortwave radio bands in dath ilan are kept clear, except for regularly spaced audible ticks broadcast all around the planet, whose spacing tells you what frequency you're on and that your shortwave radio is working correctly.

Shortwave radios don't use clever computer-compressed transmission protocols.  That would require an inscrutable computer chip, instead of a circuit board all of whose connections you could potentially check by hand using a multimeter.  The standard protocol directly transduces voices to amplitude modulations, in a way you could send or receive in the aforementioned cave using your box of scraps.

There is often a computer chip on board a shortwave radio, if it's fancy expensive emergency equipment.  But it's not a required chip--you could yank the chip out of the circuit board if you decided you were suspicious of it, and the radio would still work.  The chip is designed not to have the physical capability to send outputs that prevent the radio from working.  What the chip does do is gently diagnose every part of the system using secondary wires; for regular self-tests, or to light a red indicator light if you've had the incredible bad luck to lose ordinary satellite comms during a solar flare.

"We have a green light on the shortwave.  I am not hearing any ticks."  He doesn't add, 'that's not good', because this would convey no additional information.

"First-order-belief-formed about next-actions."

"I have:  Bring in additional flight crew member in case we are somehow both missing something very obvious.  You check our backup papers for the timing of a switch to backup flight route and prepare to fly that route based on inertial guidance.  I go public."

"Same."  He gets out of his chair and goes to the cabinet with the spiral notebooks full of auxiliary info.

Their previously planned route will take them way too close to populated cities for this to be in any sense okay for an airplane that has lost all comms to do.  So before the plane set out, as a matter of routine, Air Traffic Control printed backup routes the flight could shift to in case of an exception that caused them to seem unsafe; a route that would take them to a failover emergency landing field on a flight path that did not scare any skittish major cities or nuclear power plants.

The airplane will turn into that alternate corridor at a predictable exact clock time, based on a broad time window for when the emergency started; such that anyone who knew roughly when the airplane transponder failed would be able to predict exactly when they'd turn into the alternate corridor and exactly where they'd be, even without using satellite surveillance info.

She flips on the flight-crew-only intercom.  "Steward to cockpit, urgency 7."

An otherwise unoccupied steward will head over to the airlock system granting access to the cockpit.

The Captain pokes the First Officer to be attentive and ready to act, and then checks over the steward in the airlock over more carefully than usual through the peepholes.  They are very confused right now, possibly some Sophisticated Criminal is fucking with them, and maybe this guy is about to try to steal control of the aircraft.

"What's up?"

She gives him an abbreviated report of events, containing no inferences or explanations whatsoever, just what they observed, what they did, what they observed.

"Do solar flares do that?"

"According to me, the zero-warning first front of a solar flare does not block all of those radio frequencies simultaneously.  Furthermore if noise is blocking transmissions, the primary radios should show that in indicator lights and it should be directly audible as noise on the shortwave."

"I've got no mundane explanations.  Obvious non-mundane explanation, the criminal conspiracy hiding in the shadows of Civilization finally made their move and they simultaneously took out the satellites and the shortwave emergency stations as part of their opening play."

"But we're not obviously missing anything mundane or somehow thinking very unclearly in lockstep?"

"Not to me.  Point out the actual indicator lights you see as red so I can check your direct sensory perceptions."

A couple of minutes later, she sends out the Blue Steward with instructions.

A few minutes after that, once the Blue Steward's had time to pass it on the flight crew, she hits the planewide announcement button.

"Attention.  Attention.  This is the Flight Captain speaking."

"Exception in progress.  Not immediately fatal.  Tick 20."

"Thaaat's not a good sign about the causes of the mysterious Network failure," Keltham says, but quietly, because a lot of other people are probably saying the same thing and sudden noise-babble is not helpful during in-flight emergencies.

"We have simultaneously lost all satellite-based comms on frequencies 1.5GHz for global positioning, 3.5GHz transponder lock, Network uplink 70GHz.  That covers systems located at front and rear of plane.  Local diagnostics show equipment claims to be functioning but is reading only silence.  Failover shortwave on 14.3MHz shows green internal diagnostics but complete silence including of background ticks.  We weren't prior-warned of any expected solar weather which could do that.  Observation out the window confirms that we are not in a thunderstorm, no thunderstorms predicted nearby.  Radio noise from that or a solar flare would be directly audible on the simplified shortwave design.  Flight crew member Blue Steward has personally confirmed our direct sensory experiences on this."

"Standard protocol doesn't cover this exact situation.  Following general category protocol we will turn in 27 minutes and follow an alternate emergency flightpath to a coastal airfield where we can safely land without any functioning comms.  Default plan to meliorize against:  We are waiting 15 minutes to try to let any comms-equipment-destroying phenomena subside, then turning on the secondary shortwave to see if we can transmit between our backup shortwave and primary shortwave to confirm whether both radios are working and the apparent radio silence is probably real."

"Green Steward is trained in running emergency local prediction markets in case of comms failure.  Please don't set up new central markets unless you think you've got something important.  If you've got high-reliability direct-relevant information or what you're pretty sure is a critical insight, stake 100 unskilled-labor-hours against minimum bounty 10000 $ULH to pass to a crew member.  If there is a Keeper on board or a socially acknowledged supergenius or technical genius, please identify yourself to the crew."