Private airlines will explain before the Delhi High Court the reasons for imposing a Rs 150 per head surcharge to meet additional fuel expenses while aircraft hover over major airports due to air traffic congestion.This comes in the wake of the High Court asking the Civil Aviation Ministry to explain how the airlines have decided to impose the congestion surcharge. State-owned Indian is the only carrier that has not imposed it."Majority of the airlines have written to the Directorate General of Civil Aviation (DGCA) that they are unable to withdraw the surcharge.As we have explained to the ministry, we will implead ourselves and explain to the court why the surcharge was imposed," Kingfisher Airlines chief Vijay Mallya told reporters on the sidelines of the Airport and Airline Expo here.Following the High Court directive, the airlines had been asked by DGCA to give their point of view on the surcharge by March 24.Mallya, who is a prominent member of the industry body Federation of Indian Airlines, said if the airlines decided to withdraw the surcharge and increase air fares by the same amount, "Will it be correct?".Air fares are not regulated by the government and airlines are free to fix the rates, he said. "Therefore, the (congestion) surcharge should not be looked at with hostility", he said, adding: "As and when the situation eases and there is no congestion, every airline will be happy to remove it."