This is a report I prepared for a client last year about the fog, but it still has relevance today.
Indira Gandhi International Airport (DEL/VIDP) is located at 28°33' 59" North, 77°6' 11" East at a field elevation of 776 feet above sea level. The airport services the metropolitan area of the city of New Delhi (pop. 13,780,000) and is physically located on the outskirts of the nearby town of Gurgaon, Haryana.
The airport is the second busiest in India and serves as the primary international gateway to North India with service from 38 international carriers in addition to flag carrier Air India. It also serves as a hub for domestic carriers Indian Airlines, Jet Airways and Air Sahara. The airport averages 237 daily scheduled commercial movements with daily averages of 23,285 passengers and 667.9 tons of cargo.
The geographical location of Delhi unfortunately is unkind to meteorological conditions at the airport. During the coldest time of year from mid-December to mid-February, the cold dry air coming off the nearby Rajasthan desert tends to drop atmospheric temperatures closer to the dew point temperature. As a result, radiation fog tends to form as the mercury falls during the late evening hours. The fog is exacerbated because of the high levels of ambient pollution from the urban area. The fog usually burns out as the sun rises and temperatures increase during the morning hours.
The primary runway at DEL is runway 10/28 which is 12,500 feet long. Prior to 2001, the runway was equipped with ILS CAT II
systems which proved inadequate for operations during severe fog conditions. During the 2000-2001 winter season, conditions below CAT II
minima (DH 30m, RVR 350m) existed on 53 separate days. As a result, airlines were forced to divert in excess of 200 inbound commercial flights to alternate airports primarily Mumbai (BOM/VABB), Lucknow (LKO/VILK) and Ahmedabad (AMD/VAAH) located 613nm, 222nm and 408nm respectively from DEL. Airlines were also forced to cancel or reschedule in excess of 500 additional flights.
Following public outcry and pressure from tenant airlines, the Airport Authority of India (AAI), operators of the airport, made a decision to upgrade avionics at the airport to CAT III-A standards for the 2001-2002 winter season. This involved installation of an ASDE ground radar system, centerline lighting systems and RVR equipment along runway 10/28. Accordingly, the runway 28 instrument approach was certified to ICAO CAT III-A standards by the Indian Directorate General of Civil Aviation (DGCA) in December 2001. However, delays with the training of equipment operators to the relevant standards forced AAI to delay the official introduction of CAT III-A capabilities until the 2002-2003 winter season.
Unfortunately during the 2002-2003 winter season, fog of unprecedented severity was experienced. Conditions below CAT III-A minima (DH zero, RVR 200m) existed on 36 separate days, again causing disruptions to scheduled operations. Nonetheless, a total of 58 movements by 16 different operators were accomplished under CAT III-A conditions during the season, primarily by Air India’s Boeing 747-400 aircraft.
Whereas Air India has trained their entire cadre of Boeing 747-400 pilots to CAT III-A standards, the incumbent domestic airlines have not followed suit. Indian Airlines currently has only 12 out of almost 400 pilots certified for CAT III-A operations on their Airbus 320 aircraft, with an additional 23 expected to complete training by December 2003. Air Sahara and Jet Airways each have zero pilots appropriately certified.
For the 2003-2004 winter season, a number of international carriers have taken the drastic step of rescheduling their operations to DEL to avoid the risk of fog delays, despite the disruption to aircraft rotations and hub scheduling that this involves. British Airways will reschedule their daily Boeing 747-400 flight from London Heathrow (LHR
/EGLL) for a 1030LT arrival and 1230LT departure between 15-Dec-03 and 8-Feb-04 instead of the regularly scheduled 0125LT arrival and 0325LT departure. Cathay Pacific Airways will reschedule their Airbus 330-300 flight from Hong Kong (HKG
/VHHH) for a 1320LT arrival and 1435LT departure instead of the regular 0155LT arrival and 0720LT departure. Both carriers made this decision even though the new schedules will cause Delhi passengers to misconnect with their respective hub banks of North American flights that account for a significant chunk of Delhi-origin traffic. Other carriers including Austrian, Thai Airways International, Singapore Airlines and Asiana Airlines have also rescheduled their flights by 2 hours or more during the December 2003 to February 2004 period to avoid the 2300LT to 0700LT period where the risk of fog is greatest.
Some major operators to DEL including Air Canada, KLM, Deutsche Lufthansa AG
and Air France have not made any significant schedule changes yet, but will be monitoring the meteorological conditions closely and examining the need to possibly reschedule their operations at a later time. If forecasts warrant, Air India, the largest international operator at DEL, will implement its annual fog management plan of running Boeing 747 “shuttle service” for DEL passengers to/from the primary hub in BOM and operating all scheduled DEL-origin flights nonstop from BOM instead.
"The A340-300 may boast a long range, but the A340 is underpowered" -- Robert Milton, CEO - Air Canada