How turbulent is LHR-DEL typically?

Smooth outside monsoon season; short convective bumps between June and September.

What is the best altitude to avoid turbulence on LHR-DEL?

Cruise at FL350 or above and deviate around cells. Monsoon storm tops are high, so lateral avoidance does most of the work.

When is the best time of year to fly LHR-DEL?

October to May, outside the monsoon. Flights between June and September see the most convective activity.

What causes the turbulence on this route?

Monsoon thunderstorms and the strong vertical air movement inside and around them.

Turbulence forecast LHR → DEL. London Heathrow to Delhi. SkyBriefing.

London to Delhi: what the LHR to DEL corridor looks like

Departure: London Heathrow Airport, London, the United Kingdom
Arrival: Indira Gandhi International Airport, Delhi, India
Great-circle distance: 6,731 km (3,634 nm)
Typical airborne time: 8h 20m
Usual cruise levels: FL340 to FL400
Initial track: eastbound

Route overview

The LHR to DEL sector connects London Heathrow Airport in London, the United Kingdom, with Indira Gandhi International Airport in Delhi, India. Measured along the great circle the two airports are 6,731 km apart, roughly 3,634 nautical miles, which is close to 8h 20m in the air before winds and routing are taken into account. The initial track is eastbound, and the middle of the route sits in mid latitude latitudes.

Leaving London

Heathrow sits in the flat Thames valley west of London. There is no terrain to shelter it, so Atlantic frontal wind reaches the field directly and makes winter climb outs the busiest phase of many flights here. The great-circle track leaves LHR eastbound, and the first waypoint band of the flight sits close to 45.7N 18.9E. On a sector of 8h 20m, the climb to cruise takes roughly the first twenty to twenty five minutes.

Monsoon season convection

Along the way the track passes over high latitude airspace where the polar jet stream lives. The midpoint of the LHR to DEL track lies near 40.0N 38.3E, about 3,366 km from London, which is where the corridor spends its longest continuous stretch at cruise level. This corridor is shaped by the monsoon cycle. In the wet months convective cells cluster along the coastal section of the track, and the crew works around them with radar. In the dry months the cruise is generally smooth, with light movement limited to climb and descent.

Cruise altitudes on this sector

Long haul crews normally start cruise around FL340, then step climb toward FL380 or FL400 as the aircraft burns off fuel and can hold a higher level. Choice of level matters because turbulence is layered: a change of two or three thousand feet often puts the aircraft into calmer air, and that is one of the first adjustments a crew will request.

Arriving into Delhi

Arrivals into Delhi descend across flat plain terrain. In the pre monsoon months dust laden thermals reach several thousand feet, which is the usual explanation for the bumps on the last part of the descent. Descent normally begins around 34.3N 57.7E, roughly 1,683 km before DEL, and takes about half an hour from cruise level to touchdown.

Seasonal pattern

June to September is the monsoon window and the most convective part of the year on this corridor. October to May is normally quiet at cruise level.

Flying this route with less worry

It is worth remembering that turbulence of the kind found on the LHR to DEL track is uncomfortable and entirely within what the aircraft is built for. Wings are designed to flex, the flight is planned around the forecast, and the crew adjusts level or track when it helps. The live forecast above shows the current picture for this corridor so there are fewer surprises on the day.