Assuming that the plane is in flight and in perfect conditions but all of a sudden the whole flying crew is incapacitated: now can a passenger without any flight experience land the plane only by remote radio help? All modern liners are equipped with ILS (instrumental Landing System) that theoretically can safetly land the airplane by itself (ILS is normally used to land in severe weather conditions and/or with very limited visibility): so, again, can a passenger land the aircraft? the answer is 98% NO.
Here is the explanation.
Cabin Crew: usually (above all on liners used in long haul flight) one member of the cabin crew (flight assistants) is trained with basic infos about how to overtake pilots’ main functions. So there are many chances for him/her to safetly land the plane with radio assistance.
Panic and disorientation. Passengers are not familiar with the mass number of knobs, buttons, keys, levers and instruments that litterally cover the cockpit. So it could be very difficult for him/her to quickly locate the radio panel, check or set the proper frequency and getting in contact with remote radio assistance, especially under a high dose of stress and panic produced by the event. Last but not least all ATC communications take place in English and not all passengers are familiar with this language.
Time. Time is a crucial factor in caso of emergency. Recent simulations carried out in flight simulator showed the avarage time for a pasenger to get in radio contact with ATC or Ground facilities is approx. 15 minutes. And every minute flown means less quantity of fuel remaining to attempt an emergency landing.
Piloting procedures. Leaving cruise altitude, starting the descend to the airport, activating the approach and final landing phases are all procedure that requires at least some basic operations with the Autopilot, the Flight Director, the ACARS system and some manual actions (extending flaps, landing gears, operating the breaking system a.s.o.). The passenger under stress and panic might wrongly understand remote radio instructions or fail or mistake some of theese operations.
Weather conditions. Jet stream, CAT, windshare etc. are potentially dangerous conditions that normally are avoided by pilots (monitoring meteo radar). But what if a passenger with no previous flight experience find him/herself right in a middle of heavy or severe turbolence? Can he/she getting out of it with no further damages to passengers or to the aircraft?