new delhi us government officials in 2014 revealed an alarming safety issue passenger cellphones and other types of radio signals could pose a crash threat to some models of boeing 737 and 777 airplanesmore than 1300 jets registered in the us were equipped with cockpit screens vulnerable to interference from wifi mobile phones and even outside frequencies such as weather radar according to the federal aviation administration which gave airlines until november 2019 to replace the units made by honeywell international incread alsowhat can explain 737 max 8 crasheschina indonesia and ethiopia where the latest crash involving a boeing 737max 8 occurred on sunday killing 157 people have grounded the plane while indias civil aviation watchdog dgca has directed indian carriers to ensure that only pilots with 1000 hours and copilots with 500 hours oftoday potentially hundreds of planes worldwide are still flying with the unsafe systems cited in the faa report flightcritical data including airspeed altitude and navigation could disappear and result in loss of airplane control at an altitude insufficient for recovery the faa said in the safety bulletin known as an airworthiness directivehoneywell hasnt heard of any blanking display screens caused by cell phones or other radio frequencies while an airplane was in flight spokeswoman nina krauss said when airlines and honeywell argued that radio signals were unlikely to cause safety problems during flight though the faa countered that it had run tests on inservice planes and the jets flunkedboeing co found the interference in a laboratory test in 2012 and hasnt seen similar issues on other aircraft a company spokesman said honeywell is aware of only one case where all six display units in a 737 cockpit went blank krauss said the cause was a software problem that has been fixed and is currently being flighttested she saidthe affected 737s are the socalled next generation model a predecessor of the boeing max which was involved in two crashes in less than five months cockpit displays on the max were made by rockwell collins now a unit of united technologies corp not honeywell boeings 777s also were covered by the faa orderthe faa order didnt quantify the amount of radio signals needed to cause interference problems an agency spokesman said thursday that the faa bases the compliance time for its airworthiness directives on the risk that a condition poses a 60month compliance time frame means the risk is low and does not need to be addressed right away he saidstill the radiosignal threat extends beyond that specific display system and faa warningnumerous cell phones left on during any airplane flight could be a real problem said professor tim wilson department chair for electrical computer software and systems engineering at embryriddle aeronautical university the greater the number of phones emitting radio signals he said the greater the potential for interference with a planes flight systemairplane modemany airlines now permit passengers to turn their phones to airplane mode which allows wifi transmissions but mobile phones operate at higher