New Delhi: Union Civil Aviation Minister Jyotiraditya Scindia said Wednesday that Delhi airport’s second CAT III-enabled runway — capable of handling landing and take-offs with minimum visibility — will become operational this week. He, however, added that the majority of aircraft operating in India are not designed for operating in such low visibility conditions.
CAT III runways can handle takeoffs and landings when visibility extent is as low as 50 metres.
Scindia’s statement was part of his rebuttal to Congress MP Shashi Tharoor, who in a post of social media platform X (previously Twitter) had alleged that the ongoing fog-induced chaos at Delhi Airport and passenger inconvenience was “a Modi Govt-made disaster, a result of the Ministry of Civil Aviation’s neglect and incompetence”.
The dense fog that has engulfed northern India for the past few days has impacted hundreds of daily flights at Delhi airport, with flights facing cancellations, diversions, or significant delays.
This not only left thousands of passengers stranded and frustrated at the Delhi airport, but had a cascading effect on much of the airline network in the country. With one more CAT III runway likely to become operational this week, the Delhi Airport will have a total of two such runways, which is expected to ease the fog-related disruption.
Following backlash owing to unprecedented chaos at the Delhi airport Sunday evening and early Monday morning because of fog conditions, the Union government clarified that CAT III runways cannot handle zero-visibility operations, which is what they said was the case on those days.
The civil aviation minister, however, claimed that the number of CAT II & III trained pilots has gone up from 2,416 in 2014 — the year Prime Minister Narendra Modi took office for the first time — to 6,191 at present.
“Further, in preparation for the fog season of 2023-24, due to our efforts, the number of CAT II/CAT III trained pilots have grown by 16 percent in the last three months alone from 5,332 to 6191,” he added.
ThePrint looks at what is CAT and Delhi airport’s CAT status.
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Categories of ILS and CAT III
Category III (or CAT III) is a category of Instrument Landing System (ILS) — a means of navigation used in aviation for precision approach and landing operations during low visibility conditions. The key components of ILS are the localiser — which is used for lateral (or sideways) guidance — and glidepath, which provides vertical guidance to the pilot during the approach.
The system also includes specialised approach light systems that help pilots identify the runway environment in low-visibility and markers that help pilots in establishing their position. To land using ILS, a pilot must first align the aircraft with the runway, with the help of the localiser, and then, using the signal from the glideslope, begin the gradual descent.
ILS has three performance categories. In CAT I, landings can be executed with a decision height (the lowest height or altitude while approaching descent) of not lower than 60m (200ft) and the runway visual range not less than 550m. In CAT II, runway decision height cannot be lower than 30m (100ft) and the visual range can’t be less than 350m.
CAT III is subdivided into three categories: CAT IIIA, where the runway visual range is not less than 200m, CAT IIIB, where runway visual range is less than 200m but not less than 50m, and CAT IIIC, which has no runway visual range limitations. There are no decision height limitations for CAT III.
Two of the four runways at Delhi Airport are CAT IIIB enabled, only one of which is currently operational.
Current status of Delhi airport
The Indira Gandhi International airport is among the biggest and busiest airports in India. It has a total of four runways. However, only three are currently operational.
Of the three operational runways, only one is CAT III enabled, meaning that only this runway can currently support landing and take-offs in low visibility conditions. The fourth runway at the Delhi airport is also CAT III enabled. However, it has been closed for repairs since September last year.
Referring to the clarification by the ministry on Delhi Airport’s CAT IIIB runway, Tharoor pointed out that there is an even higher category of instrument landing called CAT IIIC, which can land at zero visibility.
“All the way back in 2008, the UPA government [Congress-led United Progressive Alliance] could ensure a CAT IIIB runway. 16 years have passed since then, with 10 years under the present government. Still, they have yet to even plan a single CAT III-C runway. Across the world, major international airports have multiple CAT III-C runways, but India does not even have one, despite its capital city’s woeful fog & smog issues in winter. Why not?,” he questioned.
In his reply to the Congress MP on X, Scindia said there are three factors for CAT III landings: runway capability, aircraft capability, and pilot accreditation.
He added that while the two CAT III runways at Delhi Airport are equipped for aircraft to land with minimum visibility of up to 50 metres, the majority of the aircraft fleet in India i.e “Airbus 320 (75 mtrs) and Boeing 737 Max (175 mtrs) have visibility minima greater than the runway threshold”.
“Thus, even if the runway is capable and sufficiently trained CAT III pilots are made available, these aircraft are not designed for zero visibility operations,” he added.
He further claimed that the John F. Kennedy International Airport, New York, has four runways, of which only one is capable of CAT III landings. This runway too is “also with a restricted minima up to 182 mtrs (600 feet) – 3.5 times of India’s 50 mtrs!”
According to a blog by Flightradar24, a service that shows real-time aircraft flight tracking information, CAT III-C approaches are typically not flown in practice.
“Whilst some major airports (such as LHR [Heathrow] and JFK) and some aircraft are certified to land in what is effectively zero visibility, there are presently no systems available that allow an aircraft to taxi to the gate in such conditions,” the blog noted. “As such, CAT III-C approaches are typically not flown in practice. The lowest operational conditions are CAT III-B.”
It also noted that CAT III-C systems can be three to four times more expensive to operate than CAT III-B.
(Edited by Poulomi Banerjee)
Also read: Delhi airport fully operationalises one runway for low-visibility landings, ‘war room’ set up