ENR 1.3 INSTRUMENT FLIGHT RULES
1. RULES APPLICABLE TO ALL IFR FLIGHTS
1.1 Aircraft Equipment
Aircraft shall be equipped with suitable instruments and with navigation equipment appropriate to the route to be flown.
1.2 Minimum Levels
Except when necessary for take-off or landing or when specifically, authorised by the appropriate authority, an IFR flight shall be flown at a level which is not below the minimum flight altitude established by the State whose territory is overflown, or, where no such minimum flight altitude has been established:
a) over high terrain or in mountainous areas, at a level which is at least 2000 FT above the highest obstacle located within 8 KM of the estimated position of the aircraft;
b) elsewhere than as specified in(a), at a level which is at least 1000 FT above the highest obstacle located within 8 KM of the estimated position of the aircraft.
Note: The estimated position of the aircraft will take account of the navigational accuracy which can be achieved on the relevant route segment, having regard to the navigational facilities available on the ground and in the aircraft.
1.3 Climb and Descent
1.3.1 Minimum Rates
Pilots climbing or descending in accordance with an ATC clearance shall inform the controller whenever it is anticipated that the vertical speed during the level change will be less than 500 FT per minute or if the actual speed in the climb or descent is less than 500 FT per minute.
1.3.2 Leaving (Vacating) a Level
When instructed to report leaving a level, pilots shall only advise ATC that they left the assigned level once the aircraft’s altimeter indicates that the aircraft has actually left the assigned level and is maintaining a positive rate of climb or descent.
1.4 Change from IFR flight to VFR flight
1.4.1 An aircraft electing to change the conduct of its flight from compliance with the instrument flight rules to compliance with the visual flight rules shall notify the appropriate air traffic services unit specifically that the IFR flight is cancelled and communicate thereto the changes to be made to its current flight plan.
1.4.2 When an aircraft operating under the instrument flight rules is flown in or encounters visual meteorological conditions, it shall not cancel its IFR flight unless it is anticipated, and intended, that the flight will be continued for a reasonable period of time in uninterrupted visual meteorological conditions.
2. RULES APPLICABLE TO IFR FLIGHTS WITHIN CONTROLLED AIRSPACE
2.1 IFR flights shall comply with the provisions of 3.6 of ICAO Annex 2 to the Convention on International Civil Aviation when operated in controlled airspace.
2.2 Except whenever otherwise indicated in air traffic control clearances or specified in the Aeronautical Information Publication (AIP), an IFR flight operating in cruising flight in controlled airspace shall be flown at a cruising level, or, if authorized to employ cruise climb techniques, between two levels or above a level, selected from:
a) the table of cruising levels in Appendix 3 of ICAO Annex 2; or
b) a modified table of cruising levels, when so prescribed in accordance with Appendix 3 of ICAO Annex 2 for flight above FL410.
2.3 All IFR flights are required to carry a functioning Mode C SSR transponder when operating in class A, C or class D airspace.
2.4 Non-functioning SSR transponder equipment must be reported to ATC immediately. ATC radar procedures are based on the carriage of this equipment and may require certain restrictions in the case of non-functioning equipment.
2.5 An aircraft, intending to depart from an aerodrome or landing site without an ATS unit which will subsequently require an IFR clearance but has been unable to obtain the clearance shall remain outside of controlled airspace until receiving such clearance, except where remaining outside of controlled airspace would require the aircraft to remain below the minimum level described in 1.2, in such cases the aircraft may climb to the minimum level applicable for the safe conduct of the flight.
2.6 Flights operating at FL280 or above
Flights operating at FL280 or above within Muscat UTA and in controlled airspace and airways outside the UTA within the Muscat FIR shall be operated in accordance with RNAV1/RNAV5 navigation requirements.
2.7 SID and STAR
The flight crew shall comply with published SID and STAR speed restrictions unless the restrictions are explicitly cancelled or amended by the controller.
2.8 Instrument Approach
The approach control unit shall specify the instrument approach procedure to be used by arriving aircraft. A pilot may request an alternative procedure and, if circumstances permit, should be cleared accordingly.
2.9 Visual Approach
2.9.1 An IFR flight may be cleared to execute a visual approach provided the pilot can maintain visual reference to the terrain and:
a) the reported ceiling is at or above the level of the beginning of the initial approach segment for the aircraft so cleared; or
b) the pilot reports at the level of the beginning of the initial approach segment or at any time during the instrument approach procedure that the meteorological conditions are such that with reasonable assurance a visual approach and landing can be completed.
2.9.2 Visual approaches by night will not be authorized unless the pilots' reports show that they have and can maintain the aerodrome in sight.
2.9.3 Pilots are responsible for their own terrain clearance when executing a visual approach and should ensure that the flight remains within controlled airspace while manoeuvring for the visual approach.
Note: ATC may limit the descent of any flight that meets the requirements for a visual approach by using the phrase:
• MAINTAIN (level) [TO (significant point)];
• MAINTAIN (level) UNTIL PASSING (significant point);
• CROSS (significant point) AT (or ABOVE, or BELOW) (level);
• NOT BELOW (feet) Until established [Position].
2.9.4 ATC will provide separation between an aircraft cleared for a visual approach and all other aircraft unless reduced separation minima in the vicinity of aerodromes is being applied according to DOC 4444 Chapter 6, 6.1 applies.
3. RULES APPLICABLE TO IFR FLIGHTS OUTSIDE CONTROLLED AIRSPACE
3.1 Cruising Levels
An IFR flight operating in level cruising flight outside of controlled airspace shall be flown at a cruising level appropriate to its track as specified in:
a) the table of cruising levels in Appendix 3 of ICAO Annex 2, except when otherwise specified by the ATS Unit for flight at or below 3000 FT above mean sea level; or
b) a modified table of cruising levels, when so prescribed in accordance with Appendix 3 of ICAO Annex 2 for flight above FL410.
3.2 Communications
An IFR flight operating outside controlled airspace but within or into areas, or along routes, designated in the AIP, shall maintain a listening watch on the appropriate radio frequency and establish two-way communication, as necessary, with the air traffic services unit providing flight information service.
3.3 Position Reports
An IFR flight operating outside controlled airspace shall report position as specified in 3.6.3 of ICAO Annex 2 for controlled flights and is required to:
a) submit a flight plan, and
b) maintain a listening watch on the appropriate radio frequency and establish two-way communication, as necessary, with the air traffic services unit providing flight information service.