The design of IFR arrival and departure procedures is the work of a procedure specialist. This person will design and check penetration of obstacle protection surfaces that encompass the entire IFR procedure. The safety buffer designed by the procedure specialist depends on the equipment being used (i.e. ILS, VOR, NDB) and the phase of flight (i.e. approach, departure, missed approach etc.). The design parameters for these obstacle protection areas are detailed in a 450 page ICAO document, 8168 Pans-Ops. The work is complex and comparable to designing a bridge. The majority of people think that the most important contribution that a procedure specialist can give to an airport is lower landing minima. This is definitely the case, however the benefits of efficiently designed procedures is a lot more involved than that.
Prior to the introduction of RNAV aircraft had to either fly towards or away from a navigational aid. Now in the RNAV environment aircraft can fly to any point in space. This flexibility in the design of IFR procedures equates to significant cost savings especially in the terminal area. Many IFR procedures that exist today were designed 30 years ago when such factors as track miles, fuel costs, noise and congestion were not as critical as they are today. Now with computers it is possible for a procedure specialist to design more efficient procedures that take these critical factors into account.
Previously Tirana airport in Albania had such procedures that required aircraft in IFR conditions to overhead the aerodrome and carry out a reversal procedure. With an efficient redesign of the arrival route by a procedure specialist, taking into account the difficult terrain, significant savings in track miles were achieved (45.5nm). Importantly, the airport was no longer capped for 16 minutes while an aircraft carried out an approach.
In Europe, environmental and noise concerns are increasing at an exponential rate while the number of flights each day also continues to increase. RNAV now allows the design of IFR procedures that enable aircraft to circumvent these sensitive areas and still be acceptable to the airline operators because of the reduced track miles flown. However these benefits can only be achieved when the procedures are designed by an experienced procedure specialist using the latest techniques and software.
Some IFR procedures at busy airports have been designed with altitude and speed gates that follow the desired continual descent profile that many modern aircraft follow to reduce noise. If the waypoints that define the gates are designed correctly by anticipating ATC radar separations a high volume of traffic can follow the arrival route with mere ATC monitoring. It is estimated that air-ground communications could be reduced by up to 40%. This will reduce pilot/controller workloads and increase traffic flow.
In some areas of the world the reliability of navigational aids is not always guaranteed. In an enroute situation the failure of a single navigational aid does not usually affect the continuation of the flight. However the situation in the terminal environment is entirely different. If a critical airport facility fails then an aircraft must divert to an alternate aerodrome. This obviously equates to a significant cost. However a GPS approach could be flown if it had previously been designed by a professional procedure specialist.
Departure tracks no longer need to intercept radials from conventional navigational aids. If RNAV departures are correctly designed aircraft can route direct. Departure procedures that take into account the capabilities of modern aircraft and reduce track miles by just 1nm on a single departure could result in a conservative saving of 3650nm a year (10 departures * 365) for a single airport. These extra track miles are flown at low altitude and represent a considerable saving in fuel costs over a year.
Efficient design of IFR procedures is safety critical and has an important impact on the operations of an airport. Not only are airline operators affected but also almost all operations on the ground. The number of aircraft that use an airport affect the profitability of an airport operation and efficient modern IFR procedures can increase this amount. With the privatisation of many airports this operational impact equates to a significant financial loss or gain.
Ian Whitworth
Managing Director
ASAP s.r.o. (Aeronautical Services And Procedures)
Prior to the introduction of RNAV aircraft had to either fly towards or away from a navigational aid. Now in the RNAV environment aircraft can fly to any point in space. This flexibility in the design of IFR procedures equates to significant cost savings especially in the terminal area. Many IFR procedures that exist today were designed 30 years ago when such factors as track miles, fuel costs, noise and congestion were not as critical as they are today. Now with computers it is possible for a procedure specialist to design more efficient procedures that take these critical factors into account.
Previously Tirana airport in Albania had such procedures that required aircraft in IFR conditions to overhead the aerodrome and carry out a reversal procedure. With an efficient redesign of the arrival route by a procedure specialist, taking into account the difficult terrain, significant savings in track miles were achieved (45.5nm). Importantly, the airport was no longer capped for 16 minutes while an aircraft carried out an approach.
In Europe, environmental and noise concerns are increasing at an exponential rate while the number of flights each day also continues to increase. RNAV now allows the design of IFR procedures that enable aircraft to circumvent these sensitive areas and still be acceptable to the airline operators because of the reduced track miles flown. However these benefits can only be achieved when the procedures are designed by an experienced procedure specialist using the latest techniques and software.
Some IFR procedures at busy airports have been designed with altitude and speed gates that follow the desired continual descent profile that many modern aircraft follow to reduce noise. If the waypoints that define the gates are designed correctly by anticipating ATC radar separations a high volume of traffic can follow the arrival route with mere ATC monitoring. It is estimated that air-ground communications could be reduced by up to 40%. This will reduce pilot/controller workloads and increase traffic flow.
In some areas of the world the reliability of navigational aids is not always guaranteed. In an enroute situation the failure of a single navigational aid does not usually affect the continuation of the flight. However the situation in the terminal environment is entirely different. If a critical airport facility fails then an aircraft must divert to an alternate aerodrome. This obviously equates to a significant cost. However a GPS approach could be flown if it had previously been designed by a professional procedure specialist.
Departure tracks no longer need to intercept radials from conventional navigational aids. If RNAV departures are correctly designed aircraft can route direct. Departure procedures that take into account the capabilities of modern aircraft and reduce track miles by just 1nm on a single departure could result in a conservative saving of 3650nm a year (10 departures * 365) for a single airport. These extra track miles are flown at low altitude and represent a considerable saving in fuel costs over a year.
Efficient design of IFR procedures is safety critical and has an important impact on the operations of an airport. Not only are airline operators affected but also almost all operations on the ground. The number of aircraft that use an airport affect the profitability of an airport operation and efficient modern IFR procedures can increase this amount. With the privatisation of many airports this operational impact equates to a significant financial loss or gain.
Ian Whitworth
Managing Director
ASAP s.r.o. (Aeronautical Services And Procedures)