Boeing bulletins warn pilots of possible worst-case 5G interference scenarios
Manju.V@timesgroup.com
23.01.2022
Mumbai: Aircraft manufacturer Boeing recently issued airline-specific bulletins alerting pilots to a long list of possible problems the cockpit could be besieged with at lower altitudes if 5G signals from a transmission station near a US airport ever happen to hazardously interfere with those of an aircraft instrument that measures accurately the plane’s height over ground.
Air India, the only Indian carrier that flies to the US, operates the route with Boeing wide-body aircraft. Other aircraft manufacturers too have issued similar documents, but the 5G effects vary. For instance: Airbus document states: “On A350 and A380 aircraft, 5G interference on radio altimeters are negligible,hence the absence of cockpit effects. ” A senior B777 commander said: “Boeing has listed everything that could possibly go wrong in the cockpit if 5G interference ev- er happens. The message pilots get is don’t attempt lowvisibility landings, the radio altimeter isn’t reliable. Also, when landing in good weather, stay extra alert after de- scending 2,500ft and be ready for a manual landing. ”
Another senior Boeing 777 commander, who is from Indian Pilots’ Guild, the Air India union with B777 pilot- members, said: “About eight out of 10 pilots will never face any of the situations listed in a bulletin. So long as the engines are working and the runway is in sight, there should be no problem. ”
What all pilots concur is, with 5G rollout in the US, the workload in the cockpit of USbound aircraft has gone up. For instance: at height below 2,500ft, pilots will now need to be alert for possible 5G interference. Boeing instructs them to monitor and crosscheck between two different altimeter readings. Above 2,500ft, a barometric servo altimeter gives altitude information by reading atmospheric pressure differences. It’s not affected by 5G waves. Below 2,500ft, aircraft systems and pilots rely on the more accurate radio altime- ter readings. But if 5G wave interference happens, the radio altimeter could fail or give erroneous readings, says the bulletin.
Capt Amit Singh, an air safety expert, said: “At extremely low temperatures, barometric altimeter readings are not accurate. Now, the radio altimeter reading too is under suspicion because of possible 5G interference. So how can a crosscheck happen between two sources that are not reliable?”
Low temperatures also can present low-visibility conditions which is when approach and landings such as CAT-III — ‘blind’ landings done by depending on aircraft instruments and ground navigation aids — are carried out.
A 5G wave interference could lead to erroneous radio altimeter readings being fed into aircraft systems. So the ‘autopilot’ functions that help carry out low-visibility landings could fail, said the bulletin. Warning systems that alert pilots to other aircraft on collision course could fail. Systems that give alerts on approaching terrain and obstacles might be rendered inoperative or function erroneously.
Capt Singh said: “During training, pilots are drilled to trust the aircraft instruments to prevent spatial disorientation during low-visibility operations. With 5G, these instruments are under suspicion. Moreover, no specific set of instructions are given in the bulletin. From a human factor/performance perspective it’s a difficult task which will add to the workload and stress. ” Capt Sam Thomas, director (India) of International Federation of Air Line Pilots Association, said: “What pilots require are unambiguous information and clear-cut risk mitigating procedures. ” He added that evidence-based study needs to be carried out before a comprehensive commentary can be made. Capt Mohan Ranganathan, an air safety expert, said: “One more reason now for pilots not to be complacent with automation. They will need to have good manual flying skills. ”
In the last three weeks, the US aviation regulator has found13 radio altimeter models to be robust enough to withstand interference.
“Aircraft models with one of the cleared 13 altimeters include all Boeing and Airbus models,” it said.
