RULES and REGULATIONS Probably no other commercial sector is subject more regulations than the airline business. The blizzard of paper needed before the airline can get airborne includes the following:
- a Certificate of Air-Worthiness (C of A) issued to the aircraft manufacturer by the government of the country where the aircraft was built.
- associated with the C of A, Flight Manuals specifying the performance, operational capabilities and limitations of all the aircraft the airline operates, including normal and emergency operating procedures.
- an Operating Certificate, issued by the government regulator to the airline after inspectors have scrutinized the minutiae of operating procedures.
- an Approved Maintenance Organization (AMO) ,again approved by the government regulator, which sets out the details of the maintenance, over haul and inspection of the aircraft.
- Crew Licenses ; these include licenses for Pilots and Air Maintenance Engineers (or Mechanics) who must undergo periodic examinations, endorsements. In addition, even though they are not licensed in most countries, the work of Flight Attendants and Dispatchers comes under the scrutiny of the regulator.
- In the case of international routes, these can only be flown after both governments have agreed on traffic rights.
Airlines also depend upon many other government authorities to provide airports, air traffic control (ATC), navigation aids, and meteorological services.
The basic mandate of ATCl is collision avoidance and it is fortunate that international agreement on standards and procedure for air traffic controls are well developed. This is thanks to the work of the International Civil Aviation Organization (I.C.A.O.), an organization affiliated with the United Nations with 185 member states. In addition to air traffic control standards, ICAO provides a wide array of recommended codes and practices which are set out in documents known as Annexes to the Convention on International Civil Aviation .
PREFLIGHT The first task involves making sure that the aircraft is ready for flight in all respects. This task begins by ensuring that that the maintenance schedule for the aircraft has been completed and all components are ready for flight. Typically, an AME (air maintenance engineer) will inspect the aircraft prior to the first flight of the day.
Next the pilots (Captain or First Officer) will do a ‘walk around ” to visually check the aircraft. As with all other phases of flight ops, the details of the procedure are listed in precise detail on a written checklist. The use of checklists is rigidly enforced by most airlines as it ensures a high level of standardization as well as compliance with best operational practices. Then, the pilots with the help of Flight Dispatch makes sure that a flight plan has been submitted to ATC prior to departure. This document sets out aircraft particulars, the requested altitude and the route and many other details.
With the aircraft inspected and the flight plan filed, boarding commences. When the passengers and cargo aboard and the doors closed, the engines are started. If positioned nose into a loading bridge, the aircraft must be pushed back after start up. Thus leaving us with the reassuring homily that even the longest journey begins with a set back. In any event, the aircraft commences it’s taxi to the runway for take -off.
TAKE OFF The rules for take off are complicated to say the least. The main issue being what to do if an engine fails while taking off. The procedure begins with the pilot calculating a speed, known as V1. These calculations take into account temperature, pressure, weight of the aircraft , runway slope and the wind component; all of which effecting the runway length required for take-off.
In the event of an engine failure at or before reaching V1 speed, the pilot must abort the take off by braking the aircraft to a stop by the end of the stopway (see diagram). If there is no engine failure through V1, the pilot raises the nose t at VR ,or rotation speed, and the aircraft lifts off the runway. Then the aircraft is flown to achieve V2, (initial climb out speed), not later than reaching a height of 35 feet.
If an engine out situation occurs after V1, a Clearway( see diagram), beyond the end of the runway, must be available to allow the aircraft to safely continue the climb..
At some “high-hot” airports, special W-A-T limits (weight altitude temperature) apply. These limits may require reductions in the aircraft take-off weight (less fuel and/or less load) particularly in the heat of midday conditions.
CLIMB OUT Typically an airliner will climb as quickly as possible to it’s planned cruising altitude. Climb performance data is available from the Flight Manual and provides the time, distance and fuel required to climb to given altitude at given take-off weight. The pilot flies at series of speeds to gain the desired climb gradient Specific headings and altitudes are stipulated for the climb out . These procedures take into account other aircraft traffic, local terrain and the alignment of the runways. Often a complicating factor is noise abatement procedures which require turns and high rates of climb to avoid noise in urban areas.
CRUISE For convenience sake and to simplify the effect of air compression with increasing speed, a measure called mach number is used instead of miles per hour when speeds exceed 250 knots. Mach number is aircraft speed divided by the speed of sound. The speed of sound in air depends upon temperature and, because temperature reduces with altitude up to tropopause, so does the speed of sound. The most significant factor in the choice of cruise altitude is outside temperature and the colder the temperature the greater the efficiency of the engine. .Wind conditions (headwind or tailwind) are also taken into account. One usually finds jet airliners operating above 30,000 feet.
The turboprop airliner must strike a balance between engine performance and propeller efficiency. The result being that turboprops cruise between 12,000 and 25,000 feet.
For any weight and altitude combination, the specifics of enroute speeds are attainable on graphs known as cruise grids. The various types of cruise conditions are identified on the grid (for example, Minimum Cost Cruise Speed). If changes are necessary inflight, new settings can be quickly determined.
DESCENT Under normal operations, a descent is planned to arrive over an at a specified location and altitude. In general, the object is to remain at cruise altitude as long as possible( because fuel consumption is lower) and, then, let down rapidly to the checkpoint. Normally the rate of descent is limited to a change of cabin pressure, which will not bother the passengers (about 300 feet per minute reduction in cabin pressure).
Approaches come APPROACH and LETDOWN Basically there are in two models; precision or non-precision. Precision Approaches are established at most major airports and consist of a station based device called ILS (instrument landing system). To-days top -end precision systems, when combined with state-of-the-art onboard avionics equipment will, allow airline aircraft to land in almost all weather conditions. At some major airports, there are several precision systems in place which typically will permit airliners to operate down to zero visibility .
At smaller places, precision systems are usually financially out of the question and, thus, these airports must settle for the much less capable ( and less safe) non-precision approach (NPA). This economy model provides only limited guidance and is designed to bring the aircraft to a point in space near the airport where the pilot can break off instrument flying, and visually maneuver the aircraft to a safe landing. Due to its cumbersome nature, the NPA is assigned higher approach limits (often 500-foot ceiling and 1 mile visibility); consequently air service to many small communities is unreliable.
LANDING Once again, the Flight Manual provides the guidance to the pilot including landing weights and temperatures. The minimum speed for final approach is a function of weight; the higher the weight the faster the landing speed. This speed is called Vref and, in large jet airliners, it can vary by as much as forty knots which , in turn, has a big impact on the amount runway required to stop. After touch down the aircraft is brought to a full stop using brakes, thrust reverse (or reverse propeller pitch in the case of turboprops) and the full application of spoilers which dump lift from the wings.
In sum, all this means that the winning pilot must have more than just straight teeth and a crocked smile.
