There are occasions when the aircraft are deliberately landed with certain amount of vertical speed, termed as ‘positive landing’

It is rather ironical but the Director General of Civil Aviation (DGCA) sent a letter on May 31 to Chief Executive Officers of all airlines and aircraft charter companies in India, instructing them not to haul up pilots for doing hard landings that are within the aircraft manufacturers’ permissible limits. The letter was issued in the wake of the disastrous end of Air India Express Flight IX 812 while landing at Mangalore on May 22, wherein late touchdown to avoid a hard landing was being quoted as one of the contributory factors which led to the aircraft overshooting the runway into a fiery and fatal heap. It had been earlier brought out by one of the national dailies that Air India had hauled up its pilots for hard landings that were technically within the manufacturers’ limits. It is being stated that Captain Zlatco Glusica, the commander of the Boeing 737 which crashed at Mangalore was hauled up in March by the airline’s flight safety department for doing a hard landing amounting to 1.7g (vertical acceleration due to gravity on touchdown, but within the maximum permissible limit of 2.1g) at Thiruvananthapuram.

The DGCA letter states, “Pilots need to be made aware that achieving a particular ‘g’ value on touchdown is no measure of a good landing. Landings should be judged not by how soft the landing has been, but if it has been made at the correct speed and touchdown zone.” It further states, “The airplane manufacturers lay down limits of ‘g’ values for landing and operators need to guard against imposing lower values.”

The DGCA’s advice cannot be questioned both in terms of its soundness and correctness, except that it also falls within the realm of ‘basic airmanship’ taught to the ‘greenhorn’ student pilots in flying clubs and not to the highly experienced airlines commanders with thousands of flying hours in their respective logbooks, to whom this should come as second nature. Actually, when an airplane comes back to earth after a flight, its return to the terra firma can be described in a number of ways ranging from a ‘hellish arrival’ to a ‘smooth touchdown’ or a ‘hard thud’ to a ‘kisser’. A pilot always aims for a smooth touchdown, without compromising on the first two ingredients, the correct speed and the correct touchdown zone.

On final straight-in approach to landing, a pilot generally controls the airplane speed with throttle(s) and aims for the correct touchdown zone by staying on the correct glide slope either visually (assisted by VASI/PAPI, etc) or by electronic means (following GCA controller’s instructions/ILS, etc). Having arrived correctly on the runway, the flare is commenced, i.e. the nose of the aircraft is raised by gently pulling back on the control column in a progressive fashion in order to arrest the vertical speed of the airplane for a smooth touchdown. A kisser landing results when the airplane is controlled in such a manner so as to achieve zero vertical speed precisely at the time when the wheels come in contact with the runway surface. A landing of this type would be perfect, provided the airplane touches down at the correct speed and within the touchdown zone.