A Gulf-based airline has conducted preliminary due diligence to evaluate a potential acquisition of troubled carrier, SpiceJet, according to people familiar with the matter. The exercise, carried out through an advisory firm a few months ago, is understood to be at an exploratory stage, with no formal proposal submitted so far. It is not immediately clear whether the airline is evaluating the acquisition of a controlling stake or the carrier in its entirety. Queries sent to SpiceJet remained unanswered till the time of going to the press.