By Chinelo Obogo
Nigeria Civil Aviation Authority ( NCAA) has issued a weather advisory circular to all pilots and airlines, saying that flights may be delayed, cancelled or the airspace could be shut down in cases of severe harmattan haze. 
The regulator mandated aviators to ensure use of the Nigerian Meteorological Agency’s ( NiMet) seasonal climate prediction to ensure safety of operations due to the dust haze.
NCAA in a circular released recently and signed by the Director General, Captain Musa Nuhu, the agency said pilots should expect moderate to severe dust haze, early morning fog along coastal areas which in some instances reduces horizontal visibility to less than 200metres.
The circular also said air- to- ground visibility would be affected and that aerodrome visibility may fall below prescribed operating minima all due to dust haze or fog.
In severe conditions, the regulator warned that dust haze or fog can blot out runway markers and air field lighting over wide visual areas making visual navigation extremely difficult or impossible.
NCAA said all these may lead to delays, diversions and/or cancellations where terminal visibility falls below the prescribed aerodrome minima.
Captain Nuhu further stated that air traffic control may close the airspace when any of the three: air-to-ground visibility, visual navigation impairment and runway markers shrouding due to dust haze is observed or forecast by NiMet
The agency mandated airline operators to ensure that necessary measures are put in place to cushion the effect of inclement weather and reduce effects delays and cancellations on their passengers.