Your Support Is Required

Aviation safety professionals, particularly Air Navigation Service Providers, are kindly invited to share experience and good practices regarding the issue described below.

Synopsis

It has been reported that in one European state, aircraft sometimes approach and land despite the reported RVR at the destination aerodrome being lower than the applicable minima for approaches/landing given in EU OPS 1, Appendix 1(Old) to OPS 1.430.

EU OPS 1 Provisions Analysis

OPS 1.340 - Meteorological Conditions

(b) On an IFR flight, a commander shall only continue towards the planned destination aerodrome when the latest information available indicates that, at the expected time of arrival, the weather conditions at the destination, or at least one destination alternate aerodrome, are at or above the planning applicable aerodrome operating minima.

OPS 1.405 - Commencement and Continuation of Approach

(a) The commander or the pilot to whom conduct of the flight has been delegated may commence an instrument approach regardless of the reported RVR/Visibility but the approach shall not be continued beyond the outer marker, or equivalent position, if the reported RVR/visibility is less than the applicable minima (see OPS 1.192.g).

(c) If, after passing the outer marker or equivalent position in accordance with (a) above, the reported RVR/visibility falls below the applicable minimum, the approach may be continued to DA/H or MDA/H.

OPS 1.430 - Aerodrome Operating Minima — General

(a) 1. An operator shall establish, for each aerodrome planned to be used, aerodrome operating minima that are not lower than the values given in Appendix 1(Old) or Appendix 1 (New) as applicable. The method of determination of such minima must be acceptable to the Authority. Such minima shall not be lower than any that may be established for such aerodromes by the State in which the aerodrome is located, except when specifically approved by that State. The use of HUD, HUDLS or EVS may allow operations with lower visibilities than normally associated with the aerodrome operating minima. States which promulgate aerodrome operating minima may also promulgate regulations for reduced visibility minima associated with the use of HUD or EVS.

In addition, other EU OPS 1 provisions also apply to low visibility operations (LVO): OPS 1.400 - Approach and Landing Conditions and OPS 1.455 - Low Visibility Operations - Operating Procedures.

Analysis

The State in question has not established and published the lowest aerodrome operating minima for its aerodromes - EU OPS 1, OPS 1.430 only says that, “…Such minima shall not be lower than any that may be established for such aerodromes by the State..”

Consequently, air traffic controllers are not aware of such limitations i.e. that for each instrument approach at a particular aerodrome there is a minima which no operator should go below. Furthermore, the controllers do not have in place a procedure(s) to act as a ‘safety check’ when a commander decides to commence an approach to land when the reported RVR is less than the specified Minima.

An example of how another state deals with this issue can be found in UK CAA/NATS AIC 100/2006 which details how the UK applies the concept of ‘Absolute Minima RVR’ (see Further Reading).

Acknowledgements

It is acknowledged that:

• Controllers are not permitted to prohibit a pilot from making an instrument approach other than for traffic reasons.
• The final decision to commence an approach in specific weather conditions rests solely with the commander of the aircraft.
• Controllers are not responsible for determining, passing or enforcing commanders’ mandatory aerodrome operating minima.

Support Requested

ANSPs and aircraft operators are invited to respond to the following questions:

1. What should controllers do when a commander indicates that he/she intends to commence an approach when the reported RVR is below the lowest minima for that aerodrome/approach?
2. What are your practices in dealing with this issue? (Note: Could also apply to take-off).

The following considerations could inform responses:

• States’ requirement to establish and publish RVR Minima for all instrument approach procedures at aerodromes.
• Controller awareness and training regarding RVR Minima.
• Controller responsibility/authorisation regarding the issuing of landing clearance when the reported RVR is below the RVR Minima.
• Controller procedures and associated phraseology.
• Controller reporting of LVO/RVR Minima related occurrences.

Further Reading

• SKYbrary
  • Commission Regulation EC 589/2008 (EU OPS 1) dated 20 August 2008.
  • Low Visibility Procedures (LVP)
  • Runway Visual Range (RVR)
• UK CAA/NATS AIC 100/2006 - Absolute Minima - dated 17 August 2006.

Summary Of Responses

1. A total of 24 responses were received; 8 from ANSPs, 13 from Aircraft Operators/Associations and 3 from National/Regulatory Aviation Authorities. The responses also included detailed extracts from one national AIPs and one Aircraft Operator’s operations manuals dealing with RVR Minima.
2. All respondents agreed that the Assumptions in the RFS were correct; it is clear that the division of responsibility between the cockpit and control room is well understood.
3. There was unanimous agreement amongst the aircraft operator respondents that the controller’s responsibilities vis-a-vis the decision of a pilot to continue an approach (or take-off) should be limited to providing the RVR values and ensuring that the runway surface is clear of obstructions.
   • [ATC should] Advise the commander and continue normal procedures; there can be no other.
   • The final decision to commence an approach in specific weather conditions rests solely with the commander of the aircraft.
   • It is the Pilot in Command’s (PIC’s) responsibility to decide, based on the company regulations etc., whether to land or not if the RVR is below the minima.
   • You can always initiate an approach, irrespective of the measured RVR; the responsibility is with the captain.
4. A similar understanding is apparent from the responses from the ANSPs. i.e controllers are only obliged to pass the weather information, ensure the runway is clear and then carry on controlling as normal.
   • It is clear what the ATCO should do: Issue approach instructions and landing clearance and, if necessary, assist the pilot during his manoeuvre.
   • I would like to strongly emphasise that the idea of enforcing (by ATC) any condition which lies in the responsibility of the air crews is unacceptable!
5. The view was also shared by two National Aviation Authorities:
   • We need to keep the ATCO out of the RVR Minima loop; they should just pass on relevant met info and control traffic as normal.
   • ATC should inform the pilot of the current RVR, and if it is low, ask intentions of the pilot. If the pilot requests the approach, clear him for the approach. ATC can NOT climb into the cockpit and fly the airplane with the pilot. The decision rests only with the pilot in command.
6. With specific regards to RVR minima it was also clear to respondents that this is the responsibility for Aircraft Operators and pilots and not ATC, e.g.
   • Controllers are not responsible for determining, passing or enforcing commanders’ mandatory aerodrome operating minima.
   • Pilots are responsible for knowing and sticking to their minima and ATC does not check the adherence to these minima.
   • It is a matter for discussion between an operator and its NAA.
   • It is impossible to require ATCOs to know the individual DH and corresponding RVR / CMV / VIS minima, which depends on the speed category and company regulations as well. It is simply not possible nor feasible to put such an extra load (and to some extend also extra responsibility) on the controllers.

   With regard to take-off, one national AIP states that:

   • A pilot on IFR flight plan shall not take off when the reported RVR or visibility, as appropriate, is below the minimum value published in the AIP. ATC will issue the official weather report. Neither taxi instructions nor take-off clearance shall be issued.
   • Phraseology: "RVR or visibility (as appropriate) ... meters. This is below published minima for take-off on runway... (runway designation). ... (call sign) taxi instructions and take-off clearance not issued".

   It goes on to say:

   • [ATCOs shall] request the pilot to state his intentions using the following phraseology :"Reported RVR and/or visibility is... This is below published minima. Advise your intentions".
7. Notwithstanding the above, one ANSP has introduced a warning to be broadcast on ATIS during Low Vis Ops: "Attention, crews of arriving traffic, check your landing minima.". Whilst another ANSP respondent stated that perhaps ATC should remind pilots to “remember [check] your minima”.
8. With regard to the responsibility (and possible liability) of controllers issuing landing clearances to aircraft they know (or suspect) are operating below any established RVR minima, there were mixed responses. In some cases it was suggested that ATC should offer conditional or discretionary clearances: e.g. “clear to land at own discretion”.

   Whilst others state that in line with the principle that it is ultimately the aircraft commander’s responsibility, the controller should issue a normal landing clearance providing the runway is clear and traffic permits:

   • ATCOs are not responsible if a pilot decides to land (or depart) with an RVR lower than the minima; their responsibility is the usual one: authorise a landing if the runway is free, and authorise a departure maintaining wake turbulence minima. During LVP you perform a lot of work to keep the runway free, and the radio beacons (mainly ILS) undisturbed, but in essence it is business as usual for a Tower ATCO.

   EUROCONTROL Note: This theme is taken forward in ICAO PANS ATM 7.10.2. which states,

   • “An aircraft may be cleared to land when there is reasonable assurance that the separation in 7.10.1, or prescribed in accordance with 7.11 will exist when the aircraft crosses the runway threshold…”

   It is important to recognise that an ATC clearance to land is not an instruction'. As described in PANS ATM 4.5.1., “Clearances are issued solely for expediting and separating air traffic and are based on known traffic conditions which affect safety in aircraft operations”. In the case of a landing clearance this means that the controller has taken the necessary actions to ensure that the runway is clear and that safe separation can be maintained from other traffic. The pilot is not bound to comply with the clearance (if for instance the weather conditions prevent a landing) but should inform the controller if they do not intend or cannot execute it.

   Moreover, ICAO PANS ATM, 4.5.1.3, clearly identifies where the division of responsibility/accountability is between ATC and the pilot-in-command regarding the execution of issued ATC clearances. [EUROCONTROL emphasis in bold'' and underline text].

   “4.5.1.3 The issuance of air traffic control clearances by air traffic control units constitutes authority for an aircraft to proceed only in so far as known air traffic is concerned. ATC clearances do not constitute authority to violate any applicable regulations for promoting the safety of flight operations or for any other purpose; neither do clearances relieve a pilot-in-command of any responsibility whatsoever in connection with a possible violation of applicable rules and regulations.”

   Thus, this provision negates the need for ATC to use discretionary type landing clearances. Controllers can issue a normal landing clearance once they have fulfilled their safety and traffic responsibilities - the decision to execute that clearance is solely the pilot-in-command’s taking into account, inter alia, any minima (including RVR) that are applicable.

9. Several respondents mentioned the concept of an ‘Approach Ban’ but this term is not universally recognised or practiced.
10. The ATC-based ‘Absolute Minima’ concept as described in the UK AIC 49/2002 was variously described as a ‘red herring’ by one respondent, that serves only to obfuscate all weather ops procedures and cause confusion and is not supported by some operators and by another as, it has outlived its purpose. On the other side of the coin, one respondent felt that Absolute Minima is a satisfactory way of advising crew that the continuation of the approach is in breach of regulatory requirements. There was general recognition though that it was only relevant in the context of CAT I operations. It was also confirmed by one regulatory body that the procedures described in the UK AIC for Absolute Minima are subject to derogation by EU authorities; therefore, they could be applied by any EU state.

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