The FAA burdened helicopter charter operators with rules to install useless radar altimeters that are now disabled by 5G

“FAA punches a hole in the U.S. economy today” (2017):

Today is the day that FAR 135.160 goes into effect. This requires a radar altimeter (“radio altimeter” in the FAA’s parlance or “radalt”) for most U.S. helicopters. The device will display the number of feet the aircraft is above the ground. Every airliner that was ever crashed into a mountain had one of these. What stopped the crashes was the terrain awareness and warning system (TAWS).

Radalt was useful in the old days because it could ring a bell for the pilots when the aircraft was, e.g., 200′ above the ground on an instrument landing system approach. If neither the runway lights nor approach lights were in sight at that point it was time to add power and fly back up into the air (“missed approach”).

Even in 2014 when this rule went into effect it was unclear why it would be a good idea to stuff a radalt (cost range: $17,000 to $100,000 depending on aircraft and whether installed new or retrofitted) into a helicopter rather than GPS+database TAWS system that can say “There is a big radio tower ahead!” or “Climb because you are about to crash into the ground.”

The new rule applies even to helicopter operations that are limited to visual flight. The chance that the pilot is looking down at the instrument panel is small (10-20 percent) because the aircraft is being controlled by reference to the natural horizon. Combine that with the chance that the pilot would be looking at the radalt number and I would say that there is a near-zero chance that a pilot in a dangerous situation would ever become aware of the radalt value.

Now it turns out that the FAA won’t allow the use of this mandatory equipment anywhere that there is 5G coverage at similar frequencies: “FAA Issues SAIB on 5G Radio Altimeter Interference”.

“AT&T, Verizon Refuse FAA Request to Delay 5G Launch” (WSJ) says “France is among the countries that have imposed wireless limits near airports while regulators study the effect the signals have on aircraft.” “AT&T and Verizon agree to postpone 5G rollout near airports by 2 weeks” (CNN) indicates that we are on track to copy the French system, but this can’t work for helicopters because the whole point of the machine is to be able to land places other than airports.

So one part of the government orders people to spend up to $100,000 on a device that has no practical value and then orders them not to use it because a different part of the government authorized transmissions that generate interference…

(What’s the practical importance of a radar altimeter failing due to 5G interference? The weather has to be pretty ugly before the radalt is essential on a modern airliner. At a typical flatland airport, the minimums for a “CAT I” ILS approach include clouds no lower than 200′ above the runway and visibility of at least 1/2 mile. If the weather is worse than this (think “fog”), there are CAT II and CAT III approaches that can be used by trained and authorized crews. These are the ones that always require a radar altimeter, which is used to inform the crew that it is time to initiate a go-around if the runway is not in sight and, for the highest level of CAT III approach, to cue the automated systems to initiate a power reduction and flare (pitch up).)

Related:

• Is 5G a total fraud?
• pilot union weighs in (some good explanations)