Instrument Procedures Chapter 10
Air Law 10-9
Radar Radar
Where radar is used for approach control, once identified by SSR a pilot may be instructed to route directly to position. In such cases the aircraft will be navigated directly to that position without compliance with the SID.
Noise Abatement Noise Abatement
SIDs reflect the preferred noise abatement routes. Initially, the SID will require a climb to 120 m (394 ft) but in practice (and to make system management easier) a climb to 500 ft is specified. At 500 ft turns may be commenced, and the pilot is required to continue the climb as required by the SID with power, gear, flaps and lift enhancers in the noise abatement configuration, and to fly at the specified speed. In an emergency, or when the PIC considers that his aircraft would be hazarded by compliance with noise abatement procedures, any power or configuration may be used, however, the operator/pilot will have to justify the action subsequently.
GNSS Procedures GNSS Procedures
The use of GNSS is approved for departure procedures in many states and procedures are published in the form of GNSS/FMS/RNAV SIDS. Where a GNSS SID is used, the pilot must have available data from non GNSS sources (i.e. VOR/DME) so that a cross check can be made to ensure the system is functioning correctly. GNSS SIDs are titled RNAV (PRNAV).
SID Chart Publication SID Chart Publication
Each state publishes SID charts in the AIP AD section as part of the entry for the appropriate aerodrome. Charts are also commercially published by Jeppesen, Aeradio, and some operators print their own (e.g. Airtours). The SARPs specify the basic information to be displayed but the commercial charts are usually far more comprehensive. If a pilot is instructed to fly a procedure for which he/she doesn’t have the chart, ATC will, on request, detail the procedure by RTF.
The following SID charts are reproductions of aerodrome procedures from the UK AIP. The first chart depicts the Midhurst SIDs from Heathrow. These departure procedures would be used for flights to Northwest France, The Channel Islands and possibly Spain and Portugal. They place the departing aircraft in a position to join airway A34 and then into A1 at FL75 and above. The Manchester SIDs via Honiley depict the route flown by flights joining A1 southbound. The final chart depicts a trial route for FMS/GNSS operations from Luton to the East and South East. Note the accuracy of the check positions for the waypoints (accurate to 1/100 of a second of longitude, approximately 30 cm).
SID Designators SID Designators
SIDs are ATS routes (see Chapter regarding ATS and Airspace). Each SID is given a unique identifier called a designator. The chart below (London Heathrow – Midhurst SIDs) shows all the current SIDs from the departure runways at Heathrow terminating at the Midhurst VOR. The route from 27R is called MID4F. The full designator would be ‘London Heathrow SID MID4F’. The number relates to the progressive series of routes. At some point in history there was MID1, the current MID series is 3 and 4. The letter shows the ‘amendment/change’ status of the SID route. When the series reaches 9 and a new series is required, the number reverts to 1. An amendment to SID MID4F would be called MID4G.
Instrument Procedures Chapter 10
Air Law 10-11
Standard Instrument Departur
Instrument Procedures Chapter 10
Air Law 10-13
The objective of an instrument approach procedure is to provide the pilot with specific track guidance such that a descent can be made to an altitude where the required visual criteria are obtained and the aircraft landed visually. The design of an instrument approach procedure is, in general, dictated by the terrain surrounding an aerodrome, the type of operations contemplated, and the aircraft to be accommodated. There are two types of instrument procedures:
Non precision approaches (an airfield approach); and Precision approach (runway approach).
Non Precision
Non Precision ProceduresProcedures
A non precision procedure is defined as an approach to an aerodrome made with reference toinstruments in which guidance is given in azimuth (laterally) only. Typically an NDB or VOR procedure is non precision.
Precision Procedures Precision Procedures
Precision procedures give the pilot guidance in azimuth (by defining a track to be flown) and elevation (by defining a glide path with reference to electronic equipment). Typically, an ILS approach is a precision procedure.
Precision Categories Precision Categories
ICAO and JARs specify categories of precision approach in terms of decision height/altitude and required runway visual range. The ICAO categories are:
Table: Precision categories Table: Precision categories
Category System Category System minima minima
Decision
Decision Height Height RVR RVR requirementrequirement
CAT I
CAT I 60 m
(200 ft)
Not less than 200 ft
Not less than 550 m or ground visibility not less than 800 m
CAT II
CAT II 30 m
(100 ft)
Less than 200 ft but not
less than 100 ft Not less than 350 m CAT III A
CAT III A Nil Less than 100 ft or no DH Not less than 200 m CAT III B
CAT III B Nil Less than 50 ft or no DH Not less than 50 m * CAT III C
CAT III C Nil No DH None
* JAR OPS specifies 75 m RVR minimum for CAT III B
Speed Speed
Aircraft performance has a direct effect on the airspace and visibility needed to perform the various manoeuvres associated with the conduct of instrument approach procedures. The most significant performance factor is aircraft speed.
Accordingly, five categories of typical aircraft have been established. Each category is based on the speed at which the pilot attempts to cross the threshold of the landing runway, Vat.(Defined as
1.3 times stalling speed in the landing configuration at maximum certificated landing mass).
This provides a standardised basis for relating aircraft manoeuvrability to specific instrument approach procedures. The instrument approach chart will specify the individual categories of aircraft for which the procedure is approved. Normally, procedures will be designed to provide protected airspace and obstacle clearance for aircraft up to and including Category D. Where airspace requirements are critical, procedures may be restricted to lower speed categories.