Here's the regulation in our manual, normal phase is landing with alt plus final reserve, abnormal is Landing with less than alt plus final but more than final
7.3 Normal phase
As long as a flight is operating in the normal phase no special conditions apply, apart from regularly checking the current weather and forecasts weather at destination and alternate aerodromes in accordance with chapter 8.1-2.3.
7.4 Abnormal phase
The decision either to continue the flight to the destination, or to divert, shall be based on planning to land with at least final reserve fuel remaining. In his decision the commander shall take into account the traffic and operational conditions, prevailing at the destination, along the diversion route to and at the en-route aerodrome considered for diversion. Preferably, final reserve fuel plus 15 minutes holding fuel should be planned as minimum remaining fuel upon landing. Since it is impossible to cover all variables related to a safe and economical flight in the abnormal phase, the following should be regarded as general guidelines and be adapted as circumstances dictate: — Replacing the original alternate by another suitable alternate demanding less fuel may be used to return to the normal phase. — Continuation of the flight to the destination in the abnormal phase may be considered with due regard to all operational circumstances. This will lead to a situation where there is no alternative left. — In-flight re-planning (significant diversion from planned route) to an adequate aerodrome may be applied to return to the normal phase. The required fuel at the point of diversion must then be at least the sum of: � Trip fuel (from point of diversion to new destination); � 3% over the newly calculated trip fuel, provided an en-route alternate is available (otherwise 5%); � Alternate fuel (new alternate for new destination); � Final reserve fuel, and � Extra fuel (when required).
NOTE: The above mentioned in-flight re-planning procedure should be in concert with Flight Dispatch. When entering the abnormal phase, the commander should consider advising ATC of the situation. When, upon reaching destination any undue delay may result in entering the emergency phase, ATC should be advised of the fuel status. Such an advisory does not guarantee traffic priority. Where applicable the term ‘Minimum Fuel' should be used, refer to OM Part C.
7.5 Emergency phase
The commander shall immediately declare an emergency when the estimated fuel on board the aeroplane upon landing will be less than final reserve fuel. The distress call 'MAYDAY' shall be used. — An emergency due to low fuel suggests the need for traffic priority to ensure a safe landing. — Report remaining usable fuel in minutes and state intentions to ATC.