Cleared to land - What does this term really mean to both Pilot and ATC?

"STANLEYAIR 502, Runway 28, surface wind calm, Cleared to Land"

Air Traffic Control (ATC), are responsible for ensuring that the runways at a Controlled airfield, are clear of any obstructions or hazards prior to issuing the Aircraft on final approach, via an Aeronautical frequency using standard radio telephony phraseology, with a landing clearance. They constantly scan the runway visually, or by using a binoculars to assist them with this task. This Radio Telephony (RT) clearance from ATC authorizes the Pilot to use the entire landing length of the runway.

The clearance from ATC can be defined as the activation of a series of positive events that ensure the safety of the flight plus its passengers at that Airfield. When the Aircraft positions on final approach for the active runway, ATC will glance towards their undercarriage as part of their Landing clearance checks, in order to verify whether it appears down and locked (visually or by means of binoculars weather dependant). Now notice I used the term `appears` in this instance because, with respect to an ATC, they do not control the selection for the undercarriage and, neither do they have any confirmation readout that the hydraulics which were selected by the Pilot in the first instance, are in fact operational. This process remains the responsibility of the PIC.

Ultimately, it is always reassuring for a Pilot to know that ATC is looking out for them in the final stages of their approach to land through the application of this visual reference. So, to recap, ATC is responsible for ensuring that the runway, which falls under their control, is serviceable and free of any obstructions and the PIC is responsible for the flight safety of their Aircraft. In the past a Mobile Runway Caravan was positioned close to the threshold of the runway in use, staffed by a Controller  OR Tower Assistant, whose job it was to observe aircraft landing or taking off and report any problems that they seen to the main Control Tower e.g. an aircraft with landing gear that appeared to be not functional etc. In modern times this procedure has been replaced electronically by CCTV and similar electronic equipment at certain Airfields globally, to uphold the visual referencing. In either instance the Pilot is relying on the ATC to give them the clearance to land on the runway, by day or night.

The introduction of Remote Air Traffic Control Towers has seen a greater demand for infrared technology designed to facilitate the ATC who is now removed from the `Live` environment, yet is still required to see the same picture from the airfield origin in real time. From the Pilots perspective they also use infrared to facilitate visual reference from outside the cockpit window, however they can only rely on an electronic indicator to varify their undercarriage is in a landing state following their manual selection, i.e. – fully deployed.

So, although the Aviation world has moved into an electronic age, with sophisticated high-tech equipment as a backup to visual reference, neither the ATC or Pilot are guaranteed that the undercarriage, (either fixed or retractable), is in fact:

1. Fully extended in the case of a retractable undercarriage (Even if the relevant indicator in the cockpit of the Aircraft is indicating as such);
2. Still has all its wheels intact in the case of both a Fixed or Retractable undercarriage;
3. Has no damage to them (such as a significant loss of air or a tear caused by foreign object debris on the runway that they originally departed from)

Getting back to the original thread of this Blog, when ATC tells an Aircraft on frequency - `Cleared to Land`, is it then an accepted fact that the ATC is fully responsible for that which they can, and cannot see on the runway in use, everytime they authorise a landing clearance, and that the Pilot is ultimately responsible for the state of their undercarriage once selected? (This statement obviously based on the resources that have been made available to either of these professions.)

Based on all the variables for both Pilot and ATC during this critical stage of flight, should this RT instruction rather be replaced with `Land at own discretion`? After all, unlike the F1 Grand Prix for example, where a team of skilled personnel are dedicated to the real time monitoring of the condition of the racing vehicle which includes its tyres, throughout the race, Aviation relies on the skill of both the Pilot and ATC to deliver a safe arrival everytime, with limitations to resources for all parties concerned.

- Dylan Kemlo