July in India arrives with the soothing sound of rain. Pilots this month mark the beginning of twelve to fourteen weeks to apply whatever skills they have learnt in clear skies and on simulators.
The July of Mumbai's CSMI Airport, which is the world's busiest single-runway operation with more than 950 air traffic movements daily, is very different. Last year, 21 July 2025, at 9:27 in the morning, Air India flight AI2744 operating the Kochi–Mumbai sector in an Airbus A320neo touched down on Runway 27 in heavy rain and veered 16 to 17 metres off the centreline crossing onto an adjacent taxiway and coming to rest with three tyres burst and one engine damaged badly. All 136 passengers and crew survived without injury.
It happens due to rubber absorption on the runway surface, which needs pre-monsoon friction restoration, rubber removal, drain cleaning. In India this exercise needs the individual inspection of more than 3,000 airfield ground lights and structural health checks on pavement. The exercise is non-negotiable and has been repeated every pre-monsoon season for years. Rubber accumulation at the touchdown zone is particularly insidious. Aircraft tyres deposit a film of nano-rubber particles on the runway at the point of spin-up, and that rubber, combined with even a millimetre of water on the surface, can reduce the friction coefficient to a fraction of its dry value. Airlines have always demanded that airports decontaminate runways.
And this is where the physics of a monsoon landing must be understood from the ground up.
A commercial aircraft lands on a contaminated runway at somewhere between 130 and 160 knots ground speed depending on weight and type. At those speeds, when the depth of standing water on the runway exceeds approximately one-tenth of an inch. The tyre, no longer able to displace water fast enough, begins to ride on a pressurised wedge of fluid. Contact with the runway surface is lost. Braking becomes nil. Anti-skid systems, which function by detecting differential wheel rotation and modulating brake pressure to maintain traction, have nothing to work against because the tyre is not rolling on pavement at all.
The anti-skid system does not activate instantaneously on touchdown. It requires the wheels to have spun up to a certain speed and begun deceleration before it can detect differential rotation and engage. A pilot who touches down too smoothly on a wet runway, with the aircraft still generating significant lift and the wheels barely spinning, will find the anti-skid silent and useless in the first few hundred metres of rollout. The prescription is a firm, definite and positive touchdown, not a gentle greaser. Plant the aircraft on the runway with positive control column input, get the weight onto the gear, deploy spoilers which both dump lift and press the wheels harder onto the pavement, then hold full brake pedal pressure and let the system work. Reverse thrust, most effective in the first five seconds after touchdown when speed is still high, should be selected immediately.
Mumbai's Runway 14 carries its own specific dossier of events. For years, aviation safety advocates and former instructors have pointed out that Runway 14 sits on a downslope, has chronically inadequate drainage, compromised by crosswinds and flooding.
Only six airports in India currently hold full Cat III B ILS certification, the system that allows aircraft to land in runway visual range as low as 50 metres. They are Delhi, Lucknow, Jaipur, Amritsar, Bengaluru and Kolkata. Delhi achieved Cat IIIB as early as 2005. Kolkata completed its dual Cat IIIB upgrade on both ends, Mumbai has Cat II capability on Runway 27, meaning a decision height of 100 feet and a runway visual range minimum of 300 metres. Chennai, Kochi, Nagpur, Varanasi and dozens of smaller stations that handle significant monsoon-season traffic have Cat I or lower ILS capability, meaning visibility minimums start at around 550 metres decision height 200 feet.
DGCA also clearly mandates that experienced crew members be rostered during active monsoon periods, that no supervised solo or newly rated first officer pairings operate in actual monsoon conditions, and that commanders maintain a conservative, safety-first posture when degraded visibility, windshear or turbulence is encountered. The circular specifically addresses ice crystal icing, a hazard associated with deep convective cells where frozen particles can accumulate in powerplant core flow paths even at temperatures outside the airframe icing envelope, and instructs pilots to navigate laterally around such areas with a minimum clearance of 20 nautical miles upwind rather than attempting to climb or descend through them.
Crosswind and tailwind technique on wet runways carries its own chapter. At Mumbai Runway 27, the dominant monsoon surface wind typically remains from 240 to 260 degrees at 15 to 20 knots with gusts to 25, generating a crosswind component of 10 to 15 knots on a runway aligned 270 degrees. The recommended technique after the flare is a de-crab followed by rudder and differential aileron to maintain centreline, with aggressive nose-wheel steering used judiciously since the nose gear on a wet runway. Reverse thrust in crosswind needs to be applied symmetrically and carefully, since asymmetric deployment on a slippery surface can amplify a yaw tendency that is already present from wind and surface friction variation.
The DGCA circular also elevates pilot reporting as a safety tool. Timely PIREPs covering turbulence intensity, windshear encounters, braking action and cloud heights are framed not as optional courtesies to following traffic but as professional obligations, part of a collective situational awareness fabric that improves safety across the sector.
Climate change is sharpening the edges of these decisions. Monsoon rains are arriving earlier, intensifying in shorter bursts, and overwhelming drainage and friction assumptions baked into older designs. This is not an abstract worry. It means more standing water, more convective towers, more rapid visibility collapses. Indian pilots now carry, in every wet‑season flight, the responsibility to fly not just the aircraft they know but the weather that is changing underneath them.
So whenever you are approaching turbulence on your route , the pilot should himself announce from cockpit to fasten the seatbelt.
Mumbai will receive its rains this July with the same indifference it has brought for centuries. The world's busiest single-runway airport will run its secondary strip in crosswinds it was not designed for.
Treat every monsoon approach as if the runway is contaminated until confirmed otherwise. When runway condition is downgraded or unknown, compute landing performance against a contaminated-runway distance, not a wet-runway figure. Ensure autobrake is set at the most appropriate setting for conditions, and do not override or cancel it prematurely.
One has to understand difference between aquaplaning when you touch down, understand aquaplaning with not stop the aircraft but a positive touchdown and after that only at 50 miles the brakes will come apply.
Go around, as an operating philosophy in monsoon, is not a last resort. It is a first option when any element of the approach picture does not correlate. Unstabilised by 1,000 feet in IMC or 500 feet in VMC, go around. Significant speed deviation on final go-around.
A concise monsoon creed for Indian crews could be written in three lines. Assume the runway is wet and shorter than it looks. Land firmly, stop decisively, and let the systems work. When anything in the picture feels wrong, climb away and try again or go somewhere else. (Capt Surjit Singh Panesar is the aviation safety expert and has been Director Flight Safety of India's National Carrier)