TAP Express (Transportes Aéreos Portugueses or TAP for short) is a Portuguese regional airline brand name for TAP Portugal which operate short- and medium-haul routes.
 TAP Portugal's lone wholly owned regional airline, Portugália Airlines, operates under the TAP Express banner.
 White Airways, an airline owned by Omni Aviation, also operates regular flights for TAP Express using 9 ATR 72 turboprops.
 Its head office is on the grounds of Lisbon Portela Airport in Lisbon.
Francisco Sá Carneiro Airport (IATA: OPO, ICAO: LPPR) or simply Porto Airport is an international airport near Porto (Oporto), Portugal.
 It is located 11 km northwest of the Clérigos Tower in the centre of Porto, in the municipalities of Maia, Matosinhos and Vila do Conde and is run by ANA – Aeroportos de Portugal.
 The airport is currently the second-busiest in the country, based on aircraft operations; and the second-busiest in passengers, based on Aeroportos de Portugal traffic statistics, after Lisbon Airport and before Faro Airport.
 The airport is a base for easyJet, Ryanair, TAP Portugal and its subsidiary TAP Express.
Portugália Airlines is a Portuguese regional airline with its head office on the grounds of Lisbon Portela Airport in Lisbon.
 It is a subsidiary of TAP Portugal and operates scheduled international and domestic services from its bases at Lisbon Airport and Porto Airport on behalf of TAP Express.
Royal Air Maroc Express is a regional airline and 100% subsidiary of Royal Air Maroc based in Casablanca, Morocco.
 The carrier operates scheduled domestic services and scheduled regional flights to mainland Spain, the Canary Islands, Gibraltar and Portugal, as well as charter services for tour operators and corporate clients.
 Its main base is Mohammed V International Airport.
Darwin Airline SA is a Swiss regional airline with its head office in Bioggio, Lugano flying under the brand name Adria Airways Switzerland.
 It has been operating scheduled domestic and international services throughout some western European countries using the brand name Etihad Regional from January 2014 until July 2017 when it was sold from Etihad Airways to Adria Airways as well as formerly also on behalf of Alitalia.
 Its bases are Geneva Airport and Lugano Airport.
Groundforce Portugal is a subsidiary company of TAP Portugal, offering aircraft ground handling services in Portugal.
 It was created with the privatization of the ground handling services of airline TAP Portugal in October 2005.
Delta Connection is a regional airline brand name for Delta Air Lines, under which a number of individually owned regional airlines operate short- and medium-haul routes.
 Delta's lone wholly owned regional airline, Endeavor Air, also resides under the Delta Connection banner.
 Mainline carriers often use regional airlines to operate services in order to increase frequency, serve routes that would not sustain larger aircraft, or for other competitive reasons.
Orbest is a Portuguese airline headquartered in Lisbon and based at Lisbon Airport, that operates scheduled and charter flights in short and long haul operations, mainly out of Portugal on behalf of tour operators but also out of Spain on behalf of its sister company Evelop Airlines.
TAP Air Portugal is the flag carrier airline of Portugal, headquartered at Lisbon Airport which also serves as its hub.
 TAP - Transportes Aéreos Portugueses - is a member of the Star Alliance since 2005 and operates on average 2,500 flights a week to 87 destinations in 34 countries worldwide.
 The company has a fleet of 90 airplanes, 68 of which manufactured by Airbus and the remaining 22 by Embraer and ATR, operating on behalf of the regional airline TAP Express.
PGA Express was a Portuguese regional airline based in Cascais at Cascais Municipal Airport.
 It was a subsidiary of Portugália (or "PGA" for short) and therefore also TAP Portugal and used to operate services to Spain in a franchise agreement with both of them.

Question: Where is the head office of a Portuguese regional airline that is a subsidiary of TAP Portugal and operates scheduled international and domestic services from its bases at Lisbon Airport and Porto Airport on behalf of a Portuguese regional airline brand name for TAP Portugal which operate short- and medium-haul routes ?
Answer: Lisbon Portela Airport