United Airlines last month asked a judge overseeing its bankruptcy case for permission to end the code-sharing and marketing agreement with regional carrier Great Lakes Aviation. According to a UAL spokesman, the request is “essentially procedural” and does not mean UAL rejects out of hand Great Lakes as a code-sharing and marketing partner. Great Lakes, which has no regional jets in its fleet, currently serves about 40 routes as United Express. UAL would like to replace five of those routes, served by Great Lakes turboprop aircraft, with regional jets operated by another existing United Express partner. The court cannot rule on an amendment to the existing partnership, but it can approve or reject that partnership in whole. If the court approves UAL’s petition to dissolve the existing partnership with Great Lakes, it would open the door to approval of a new partnership that does not include the five routes in question.