Mumbai: Two aircraft at Mumbai's Chhatrapati Shivaji Maharaj International Airport came dangerously close to one another on June 8, with just 509 metres separating them on the runway. A short while after an Air India aircraft took off for Thiruvananthapuram, an IndiGo flight from Indore touched down on the same runway.
The air traffic controller implicated in the incident has been de-rostered and an investigation has been initiated by the Directorate General of Civil Aviation (DGCA). Air traffic control may only authorize a landing when it can reasonably be assured that the aircraft landing will not cross the threshold until the aircraft taking off has gone beyond the end of the runway. This is following DGCA guidelines. It appears that someone disregarded this rule.
ATC's Response
The official response from Air Traffic Control of India regarding the incident at Mumbai's Chhatrapati Shivaji Maharaj International Airport was to clarify that arrival and departure flights are handled by the airport on a regular basis and that the conditions surrounding Air India's takeoff and Indigo's landing were safe and precautionary.
This incident raised questions about whether there are any guidelines to follow in such situations.
The guidelines in the case of runway traffic are to be followed by the Federal Aviation Administration (FAA). Certain markings on the runway need to be followed. Runway threshold markings either consist of eight longitudinal stripes of uniform dimensions disposed symmetrically about the runway centerline to help the pilot depart, taxi, or land the flight.
What Is A Threshold On The Runway?
In aviation, the threshold refers to the beginning of the runway that is usable for landing an aircraft. It marks the point at which a landing aircraft should ideally touch down on the runway. The threshold signifies the start of the portion of a runway suitable for the landing phase of an aircraft.
Same Runway Separation: Two Arrivals
When "the other aircraft has landed and is clear of the runway," an aircraft may land on a runway, per the FAA's Air Traffic Control Procedures Manual (3-10-3). However, if there are minimum distances from the landing threshold, this requirement does not apply if it is between sunrise and sunset:
Same Runway Separation | FAA
1) 3,000 Feet of Separation: When an aircraft of Category I lands behind an aircraft of Category I or II.
What are the categories of aircraft?
Category I: all-helicopters and small, single-engine, propeller-driven aircraft weighing under 12,500 pounds.
Category II: tiny, twin-engine, propeller-driven aircraft weighing no more than 12,500 pounds.
Category III: Every other aircraft type.
2) When a Category II aircraft is landing behind a Category I or II, there must be 4,500 feet of separation.
One Arrival, One Departure on the Same Runway
Separation is assured and another aircraft may land if the other aircraft is taking off and has passed the runway departure threshold.
Same Runway Separation | FAA
However, there are once more exclusions:
1) Aircraft in Category I should land 3,000 feet away from aircraft in Categories I or II.
2) A Category II aircraft landing behind a Category I or II aircraft at a separation of 4,500 feet
3) 6,000 Feet of Distance: In the event that either aircraft is a category III.
Lastly, "visual separation may be applied in lieu of using distance minimums when the training aircraft is a helicopter."
