Lots of confusion regarding this...
Would you fly on a NON ETOPS sector during 2 hours with opened airfields, but you can not land there because the weather for all of them are bellow your minimas (Europe case, October due to fog, early morning for few hours), where would you divert in case of an engine fire (one engine 60 minutes Adequate aerodrome)?
1st thing 1st, there is NO OFFICIAL definition of a SUITABLE Airport/aerodrome, only ADEQUATE Aerodrome
CAT-OPS ANNEX I
Definitions for terms used in Annexes II to V
(4) ‘adequate aerodrome’ means an aerodrome on which the aircraft can be operated, taking account of the applicable performance requirements and runway characteristics;
(43) ‘en-route alternate (ERA) aerodrome’ means an adequate aerodrome along the route, which may be required at the planning stage;
(48) ‘fuel ERA aerodrome’ means an ERA aerodrome selected for the purpose of reducing contingency fuel;
CAT.OP.MPA.107 Adequate aerodrome
The operator shall consider an aerodrome as adequate if, at the expected time of use, the aerodrome is available and equipped with necessary ancillary services such as air traffic services (ATS), sufficient lighting, communications, weather reporting, navigation aids and emergency services.
CAT.OP.MPA.140 Maximum distance from an adequate aerodrome for two-engined aeroplanes without an ETOPS approval
(a) Unless approved by the competent authority in accordance with Annex V (Part-SPA), Subpart F, the operator shall not operate a two-engined aeroplane over a route that contains a point further from an adequate aerodrome, under standard conditions in still air, than:
(1) for performance class A aeroplanes with either:
(i) a maximum operational passenger seating configuration (MOPSC) of 20 or more; or
(ii) a maximum take-off mass of 45 360 kg or more,
the distance flown in 60 minutes at the one-engine-inoperative (OEI) cruising speed determined in accordance with (b);
CAT.OP.MPA.185 Planning minima for IFR flights — aeroplanes
(a) Planning minima for a take-off alternate aerodrome
The operator shall only select an aerodrome as a take-off alternate aerodrome when the appropriate weather reports and/or forecasts indicate that, during a period commencing one hour before and ending one hour after the estimated time of arrival at the aerodrome, the weather conditions will be at or above the applicable landing minima specified in accordance with CAT.OP.MPA.110. The ceiling shall be taken into account when the only approach operations available are non-precision approaches (NPA) and/or circling operations. Any limitation related to OEI operations shall be taken into account.
(b) Planning minima for a destination aerodrome other than an isolated destination aerodrome
The operator shall only select the destination aerodrome when:
(1) the appropriate weather reports and/or forecasts indicate that, during a period commencing one hour before and ending one hour after the estimated time of arrival at the aerodrome, the weather conditions will be at or above the applicable planning minima as follows:
(i) RVR/visibility (VIS) specified in accordance with CAT.OP.MPA.110; and
(ii) for an NPA or a circling operation, the ceiling at or above MDH;
or
(2) two destination alternate aerodromes are selected.
(c) Planning minima for a destination alternate aerodrome, isolated aerodrome, fuel en-route alternate (fuel ERA) aerodrome, en-route alternate (ERA) aerodrome
The operator shall only select an aerodrome for one of these purposes when the appropriate weather reports and/or forecasts indicate that, during a period commencing one hour before and ending one hour after the estimated time of arrival at the aerodrome, the weather conditions will be at or above the planning minima in Table 1.
SPA.ETOPS.110 ETOPS en-route alternate aerodrome
(a) An ETOPS en-route alternate aerodrome shall be considered adequate, if, at the expected time of use, the aerodrome is available and equipped with necessary ancillary services such as air traffic services (ATS), sufficient lighting, communications, weather reporting, navigation aids and emergency services and has at least one instrument approach procedure available.
(b) Prior to conducting an ETOPS flight, the operator shall ensure that an ETOPS en-route alternate aerodrome is available, within either the operator’s approved diversion time, or a diversion time based on the MEL generated serviceability status of the aeroplane, whichever is shorter.
(c) The operator shall specify any required ETOPS en-route alternate aerodrome(s) in the operational flight plan and ATS flight plan.
SPA.ETOPS.115 ETOPS en-route alternate aerodrome planning minima
(a) The operator shall only select an aerodrome as an ETOPS en-route alternate aerodrome when the appropriate weather reports or forecasts, or any combination thereof, indicate that, between the anticipated time of landing until one hour after the latest possible time of landing, conditions will exist at or above the planning minima calculated by adding the additional limits of Table 1.
(b) The operator shall include in the operations manual the method for determining the operating minima at the planned ETOPS en-route alternate aerodrome.