The US Federal Aviation Administration is set to take the first step towards allowing pilots to land an aircraft using only sensors to see the runway.
A notice of proposed rulemaking will be published on 11 June in the Federal Register that would lift the requirement for pilots to rely on natural vision within 30.5m (100ft) of the touchdown point of the runway.
If the proposed rulemaking is accepted as a final rule, pilots could use an enhanced flight vision system instead that overlays real-time imagery of the runway on a synthetic graphical database of the terrain all the way to touchdown and roll-out of the aircraft.
The FAA would accept vision systems based on forward looking infrared, millimetre wave radiometry, millimetre wave radar or low-light level image intensification.
The system must allow pilots to look outside the aircraft along the flightpath, according to the notice, which would appear to prohibit Honeywell's head-down enhanced vision system.
The FAA instead would require the aircraft to use a head-up or head-mounted display for the pilot flying the aircraft. The notice also proposes to require providing the same vision system to the co-pilot, but the visual image would not have to be offered on a head-up display.
The notice also proposes several requirements for an acceptable enhanced flight vision system. Such a system would have to include the altitude of the aircraft above the ground and prompt the pilot when it is time to begin the flare manoeuvre before touchdown.
In addition to the new technical requirements, the FAA also proposes a set of training, experience and proficiency requirements for crews who use an enhanced flight vision system.
The notice is published nine years after the FAA allowed pilots to use enhanced flight vision systems to lower the decision altitude to 30.5m for landing on runways. That rule led to such systems being installed on thousands of business jets, but it still required the pilot to be able to visually identify lights or markings on the runway from 30.5m above the touchdown point.