Fuelling turbulence

A. Ranganathan

In the 1970s, when oil prices shot up ten-fold, it was considered ‘black gold’. The fortunes of several countries with large reserves of oil soared. However, this black gold is turning the bottom-line of the aviation industry a deep red.

Some airlines have resorted to flying at slower speeds to get more miles per kilolitre while others have opted to keep some of their aircraft on the ground. Fuel is a major component in the direct operating cost of an airline. The more it costs, the deeper the hole it burns in an airline’s balance-sheet.

Modern jets use the concept of ‘cost index’ in their flight management computer system to work out the optimum performance of an aircraft. When getting the maximum mileage is the priority a low cost index is used.

A high cost index is used when fuel cost is cheap and other criteria outweigh the cost of the fuel. Airlines that own their aircraft would prefer to use the lowest cost index to maximise the distance covered with minimum fuel while airlines with leased aircraft would opt to go in for higher speeds.

Why is the operating cost high in India? The following are some of the reasons that contribute to increased fuel consumption:

Outdated and inefficient air traffic control system

Unlimited congestion at terminal area

High ground time with engines running

Inadequate maintenance schedules

Improper flight procedures

Overloading

Starting with the last factor, overloading is a bane of all airlines. The fuel burn calculations are based on weight and the prevailing atmospheric conditions. The greater the weight, the lower the altitude an aircraft flies at. The overzealousness to sell tickets at ridiculously low rates is adding to this problem.

Greater weight

Every ten passengers on board means an additional tonne in total weight. This, in turn, increases the fuel burn. Passengers are also the guilty party in the overload factor. Hand baggage, which is supposed to weigh a maximum of 10 kg, often weighs more than 20 kg. Ground staff often turn a blind eye to this violation, except with some airlines.

A disciplined flight crew can contribute immensely to fuel conservation. Unfortunately, discipline and professionalism is in short supply in India. When flights are conducted with managed speeds, as calculated by the flight management computer, one can expect minimum fuel burn.

However, there is a tendency among some of the flight crew to distrust the computer Air traffic control procedures in India leave a lot of room for improvement. The air distance from one city to another, particularly in the metro routes, is often increased by a large factor because of the ATC. When congestion is anticipated, aircraft should be advised well in advance.

Instead of sequencing the aircraft in a holding pattern, where each aircraft knows the position of the others and also its number in the landing sequence, the radar controlling resorts to what is called ‘tactical radar vectoring’. This results in a large increase in air miles.


More air-miles

Often, while approaching the Delhi airport, aircraft are sent on a northerly heading for a good 35-50 kilometres before turning east or west (depending on the runway in use) for another 75-90 km, before turning back towards the airport.

This additional distance of over 150 miles is a common occurrence in Delhi or Mumbai. The aircraft fuel consumption increases due to this and this is an excess that can be avoided by using proper procedures.

In a holding pattern, an aircraft will fly at what is called the ‘best clean speed’, giving the minimum fuel burn and drag. In the tactical radar vectoring scenario, aircrafts are often asked to reduce to low speed which require the use of flaps, increasing the drag and fuel burn in turn.

The sooner India switches over to the RNAV/RNP (Area Navigation/Required Navigation performance) procedures, the better for lowering fuel consumption. These procedures are satellite based and are independent of all ground based aids.

Airlines should consider rescheduling their flights. It is better to fly a higher load factor at the optimum cruise altitude than to fly at lower cruise altitudes.

At present, with so many airlines departing around the same time and in the same direction, many of them get slotted into altitudes that are well below the optimum. This results in higher fuel burn. Cheap tickets may make for a high load factor but they give very low yield. This goes against all norms of economics at the present level of fuel cost.

The time spent on ground with engines running is an area that ATC should optimise.

The authorities have to work out a procedure whereby an aircraft should be able to depart within a maximum of 10 minutes of taxiing.

With the onset of the monsoons and fuel on board becoming critical, it is in everyone’s interest that slot times are staggered and not bunched. Somebody has to act; if not, they will go under.

(The author is an airline pilot with 35 years experience.)