IFR Procedure design is an important area of aviation that is little understood by many in the industry. However a procedure designer is the source of all IFR procedures in the world. Not only is this area safety critical to operations in the air but can also seriously affect various operations on the ground. The work done by a Procedure designer is complex and there are relatively few people in the world that actively design IFR procedures on a daily basis (approximately 500).
In most simplistic terms procedure design deals with navigational equipment tolerances which are used to define a buffer area around an aircraft which is kept clear of obstacles. The process of determining this buffer area is involved and can take up to three weeks for a single IFR procedure, even with the assistance of computers.
The safety buffer designed by the procedure designer depends on the equipment being used (i.e. ILS, VOR, NDB etc.) 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 majority of people think that the most important contribution that a Procedure designer 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. In fact the cost savings can start even before the airport is built.
Placement of a new airport is critical to its eventual success or failure. Various factors are involved in the placement of an airport but one factor that is often overlooked in the planning phase is the eventual IFR procedures and minima that will be in effect when the airport is built. ICAO document Annex 14 contains Standards and Recommended practices that prescribe the obstacle limitation surfaces around an airport that define the limits to which objects may project into the airspace. These Annex 14 obstacle limitation surfaces are obviously checked in the planning phase. However obstacles or terrain outside and under these surfaces can affect the more complex ICAO Pans-ops surfaces resulting in an adverse situation that was not anticipated by a simple ICAO Annex 14 check.
Even established Airports should seriously consider the Pans-ops procedure design issues prior to commencing any expansion work. There is no need to invest in extending a runway to accommodate Cat D aircraft when such an extension would include new obstacles and make the Landing minima unacceptable. A simple Annex 14 check is not sufficient for this type of investment. Further more, technicians tend to place navigational aids such that they have the best coverage and are closest to the power plug. However that may not be the best place to achieve the most optimal IFR procedure with the lowest minima.
Without the input of a procedure designer in the planning phase expensive work can be done that provides little or no benefit to an Airport.
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. These factors could seriously affect the attractiveness of an airport especially to low cost airlines. Now with computers it is possible to design more efficient procedures that take these critical factors into account. This combined with the flexibility of RNAV (RNP, GNSS etc.) enables the design of modern IFR procedures that reduce track miles flown and can help to alleviate traffic congestion.
Departure procedures that take into account the capabilities of modern aircraft and reduce track miles by just 1nm could result in a conservative saving of 3650nm a year (10 departures *365). These extra track miles are flown at low altitude and represent a considerable saving in fuel costs over a year.
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. This will reduce controller workload and increase traffic flow. However such speed and altitude gates can only be designed by a procedure designer taking into account the optimal descent profile, aircraft performance and most importantly ICAO document 8168 RNAV obstacle clearance criteria.
Another example, was the tendency of past procedure designers to design holding patterns overhead the main navigational aid which was usually placed on the airport. Such holding patterns capped an airport or required departing aircraft to remain at low and inefficient altitudes until clear of the holding traffic. Now with computers, the design of holding patterns at the start of the initial approach segment and clear of departures is possible. This means that departures and arrivals can more efficiently mix without extensive ATC involvement. Such optimisation requires a redesign of the holding procedures by a procedure designer.
These types of optimised procedures were not possible when many of the existing IFR procedures were originally designed in a pencil and paper environment.
One would think that such a safety critical profession would be strictly regulated but unfortunately it is not in approximately 99% of the world. At the time of writing the official requirements to be a procedure designer are..… None. However all is not lost as there has been self regulation within the Procedure designer community that has unofficially established the following minimum requirements:
1 Aviation background either pilot or ATCO
2 Completed a recognized 6 weeks Procedure design course
3 Worked with an experienced procedure designer for at least a year
Unfortunately this self regulation by professional individuals is likely to change with the introduction of IFR Procedure design software which is driven by market forces. Up until approximately 8 years ago all procedures were designed by procedure designers using topographical maps, tracing paper, a pencil and a calculator. Over the succeeding years it was quickly realized that software to design IFR procedures in a fraction of the time was a lucrative business opportunity. Various computer companies have developed Procedure designer software. At the time of writing and as far as I know, all but one have not been indorsed by any internationally recognised body but are in use by various CAAs around the world. However a single company that is a relative new comer to the Procedure designer software market seems to be endorsed by ICAO as their software is sold on the ICAO website. Why ICAO has singled out this one company for endorsement among all the others is not known and why this endorsement service is not available to the other more established companies is also a mystery.
Software that is designed for onboard an aircraft has rigorous controls in place and is extensively tested prior to authorisation by the appropriate authority. Software that is used to design the tracks and minimum altitudes that an aircraft can fly in IFR conditions is not.
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 to various extents. Obviously the numbers of aircraft that use an airport affect the profitability of the airport and efficient modern IFR procedures can increase this amount. With privatisation of many airports this operational impact equates to a significant financial loss or gain.
In most simplistic terms procedure design deals with navigational equipment tolerances which are used to define a buffer area around an aircraft which is kept clear of obstacles. The process of determining this buffer area is involved and can take up to three weeks for a single IFR procedure, even with the assistance of computers.
The safety buffer designed by the procedure designer depends on the equipment being used (i.e. ILS, VOR, NDB etc.) 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 majority of people think that the most important contribution that a Procedure designer 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. In fact the cost savings can start even before the airport is built.
Placement of a new airport is critical to its eventual success or failure. Various factors are involved in the placement of an airport but one factor that is often overlooked in the planning phase is the eventual IFR procedures and minima that will be in effect when the airport is built. ICAO document Annex 14 contains Standards and Recommended practices that prescribe the obstacle limitation surfaces around an airport that define the limits to which objects may project into the airspace. These Annex 14 obstacle limitation surfaces are obviously checked in the planning phase. However obstacles or terrain outside and under these surfaces can affect the more complex ICAO Pans-ops surfaces resulting in an adverse situation that was not anticipated by a simple ICAO Annex 14 check.
Even established Airports should seriously consider the Pans-ops procedure design issues prior to commencing any expansion work. There is no need to invest in extending a runway to accommodate Cat D aircraft when such an extension would include new obstacles and make the Landing minima unacceptable. A simple Annex 14 check is not sufficient for this type of investment. Further more, technicians tend to place navigational aids such that they have the best coverage and are closest to the power plug. However that may not be the best place to achieve the most optimal IFR procedure with the lowest minima.
Without the input of a procedure designer in the planning phase expensive work can be done that provides little or no benefit to an Airport.
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. These factors could seriously affect the attractiveness of an airport especially to low cost airlines. Now with computers it is possible to design more efficient procedures that take these critical factors into account. This combined with the flexibility of RNAV (RNP, GNSS etc.) enables the design of modern IFR procedures that reduce track miles flown and can help to alleviate traffic congestion.
Departure procedures that take into account the capabilities of modern aircraft and reduce track miles by just 1nm could result in a conservative saving of 3650nm a year (10 departures *365). These extra track miles are flown at low altitude and represent a considerable saving in fuel costs over a year.
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. This will reduce controller workload and increase traffic flow. However such speed and altitude gates can only be designed by a procedure designer taking into account the optimal descent profile, aircraft performance and most importantly ICAO document 8168 RNAV obstacle clearance criteria.
Another example, was the tendency of past procedure designers to design holding patterns overhead the main navigational aid which was usually placed on the airport. Such holding patterns capped an airport or required departing aircraft to remain at low and inefficient altitudes until clear of the holding traffic. Now with computers, the design of holding patterns at the start of the initial approach segment and clear of departures is possible. This means that departures and arrivals can more efficiently mix without extensive ATC involvement. Such optimisation requires a redesign of the holding procedures by a procedure designer.
These types of optimised procedures were not possible when many of the existing IFR procedures were originally designed in a pencil and paper environment.
One would think that such a safety critical profession would be strictly regulated but unfortunately it is not in approximately 99% of the world. At the time of writing the official requirements to be a procedure designer are..… None. However all is not lost as there has been self regulation within the Procedure designer community that has unofficially established the following minimum requirements:
1 Aviation background either pilot or ATCO
2 Completed a recognized 6 weeks Procedure design course
3 Worked with an experienced procedure designer for at least a year
Unfortunately this self regulation by professional individuals is likely to change with the introduction of IFR Procedure design software which is driven by market forces. Up until approximately 8 years ago all procedures were designed by procedure designers using topographical maps, tracing paper, a pencil and a calculator. Over the succeeding years it was quickly realized that software to design IFR procedures in a fraction of the time was a lucrative business opportunity. Various computer companies have developed Procedure designer software. At the time of writing and as far as I know, all but one have not been indorsed by any internationally recognised body but are in use by various CAAs around the world. However a single company that is a relative new comer to the Procedure designer software market seems to be endorsed by ICAO as their software is sold on the ICAO website. Why ICAO has singled out this one company for endorsement among all the others is not known and why this endorsement service is not available to the other more established companies is also a mystery.
Software that is designed for onboard an aircraft has rigorous controls in place and is extensively tested prior to authorisation by the appropriate authority. Software that is used to design the tracks and minimum altitudes that an aircraft can fly in IFR conditions is not.
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 to various extents. Obviously the numbers of aircraft that use an airport affect the profitability of the airport and efficient modern IFR procedures can increase this amount. With privatisation of many airports this operational impact equates to a significant financial loss or gain.