Block time generally refers to the time taken by a flight to travel from one point to another and is also a key factor for measuring On Time Performance (OTP) of flights.
The ministry's move assumes significance against the backdrop of slot constraints at various airports, especially those in metros, and disputes over OTP claims made by airlines.
"The process of block time rationalisation has started. It is a process that will be taken up every time a slot allocation happens or when a schedule has to be approved," Civil Aviation Secretary R N Choubey said on Tuesday.
He noted that the Directorate General of Civil Aviation (DGCA) has issued guidelines, that are free from "ambiguity", with respect to block time.
"Any data fudging can happen when guidelines have ambiguity," he said, adding that block time should be the same irrespective of the airline.
According to Choubey, the ministry has asked the DGCA as well as authorities related to slot allotments and schedule approval to constantly push for harmonisation of airlines' block time with the real block time.
"All busy airports are in focus. Slots may be difficult for an airport or during certain hours. Whenever there is slot allocation issue, then the block time (requirement) will be enforced strictly going forward," he said.
There have been instances where airlines have mentioned block time more than the actual time taken for a particular travel.
Technically, block hours refer to the span of time from the switching on of the aircraft's engines to their switching off. An airline's OTP as well as facilities and financial compensation to an air passenger in case of delay are determined on the basis of block hours.