The Federal Aviation Administration (FAA) issued a new airworthiness directive (AD)
on February 24th warning Boeing 737 operators that interference from 5G C-band
wireless broadband operations could affect radio
altimeters. The warning applies to all Boeing 737 models except 200 and 200-c series types.
This is the latest installment in the 5G rollout saga that airlines argue potentially jeopardize
the safe operations of planes near airports. The argument centers on telecommunications towers near
airports using 5G C-band frequencies. Aircraft altimeters use nearby frequencies and the fear
is any interference could make landings unsafe. Despite having two years to sort the problem,
the FAA left the matter largely unresolved. With telecom firms set to turn on their 5G networks
in mid-January, the FAA suddenly acted and issued scores of NOTAMs
(or Notice to air missions). These banned auto-landings and radio-altimeter-based automated
flight manoeuvres at 100 airports across the US. Meanwhile, airlines warned of impending chaos.
After an intervention by the US Secretary of Transport, telecom firms delayed turning
on their 5G frequencies near airports. The FAA, the Federal Communications Commission,
airlines, and the relevant telecom companies set to work to resolve the issues.
Under fire for its underwhelming preparation before the rollout date,
the FAA soon rescinded most of its bans and promised to pick up its game.
Now, in an A.D. available online, 5G and the popular Boeing 737 is back on the agency's radar.
The AD applies to Boeing 737-100, -200, -200C, -300, -400, -500, -600, -700, -700C, -800,
-900, and -900ER series airplanes equipped with a certain flight control system. Only
the 737-200 and -200C series jets equipped with an SP-77 flight control system are exempt from
this directive. It’s also important to note that the 737 MAX wasn’t included in this directive,
but was included in previously issued notices. "This AD was prompted by a determination that
radio altimeters cannot be relied upon to perform their intended function if they
experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band
(5G C-Band), and a recent determination that, during approach, landings, and go-arounds,
as a result of this interference, certain airplane systems may not properly function,
resulting in increased flight crew workload while on approach with the flight director,
auto-throttle, or autopilot engaged, which could result in reduced ability of the flight crew to
maintain safe flight and landing of the airplane." The FAA goes on to say that "This AD requires
revising the limitations and operating procedures sections of the existing airplane flight manual
(AFM) to incorporate specific operating procedures for instrument landing system (ILS) approaches,
speed brake deployment, go-arounds, and missed approaches, when in the presence of 5G C-Band
interference as identified by Notices to Air Missions. The FAA is issuing this AD to address
the unsafe condition on these products." The Boeing 737 is a workhorse across many
US carrier's fleets. There’s Southwest Airlines with its fleet of over 730 737s,
Delta Air Lines with over 230, American with over 300, and United Airlines with over 350.
It should be noted this AD is a warning - not a flight ban.
Boeing states that it issued similar advice last month to its US-based customers operating 737
aircraft. Further, the FAA has not yet advised on steps to mitigate the potential problem.
Are you worried about this directive? Or are you confident that things will be
sorted out fairly quickly? Let us know by leaving a comment.