Question: Mirza Ahmad Ispahani was the first chairman of an airline out of what main hub?

Context paragraphs:
Ahmad Shah Bahadur: Ahmad Shah Bahadur, Mirza Ahmad Shah, Mujahid-ud-Din Ahmad Shah Ghazi (23 December 1725 – 1 January 1775) was born to Mughal Emperor Muhammad Shah.  He succeeded his father to the throne as the 15th Mughal Emperor in 1748 at the age of 22.  When Ahmed Shah Bahadur came to power the rule of the Mughal Empire was collapsing, furthermore his administrative weaknesses eventually led to the rise of the usurping Feroze Jung III.

Ispahani Islamia Eye Institute and Hospital: The Ispahani Islamia Eye Institute and Hospital is an ophthalmological hospital in Dhaka, Bangladesh.  The hospital was founded by Bangladeshi philanthropist Mirza Ahmad Ispahani in 1960.

Pakistan International Airlines: Pakistan International Airlines (Urdu: ‎ ) commonly known as PIA (Urdu: ‎ ) is the national flag carrier of Pakistan.  Its main hub is Karachi while Lahore and Islamabad are its secondary hubs.

Ispahani Public School &amp; College, Comilla: Ispahani Public School & College, Comilla commonly referred to as IPSC is a well known private educational institution on Comilla,Bangladesh.  The institution offers primary, secondary and higher secondary education facilities under the Comilla Education Board.  Founded by Mirza Ahmad Ispahani in 1979 the institution is widely known for its excellent results in S.S.C. and H.S.C. exams and its discipline.

Mirza Mehdy Ispahani: Mirza Mehdy Ispahani (also known as Sadri Ispahani) (1923–2004), son of Mirza Ahmad Ispahani, was Chairman of M.M. Ispahani from 1949 till 2004.  Mirza Ali Behrouze Ispahani, son of Mirza Mehdy Ispahani was elected as the Chairman of M.M. Ispahani in 2004.

Mirza Ahmad Ispahani: Mirza Ahmad Ispahani (1898–1986) was a Perso-Bengali businessman and the patriarch of the Ispahani family based in Chittagong.  He was the founder of Orient Airways and the first chairman of Pakistan International Airlines (PIA).

Ispahani Public School &amp; College: Ispahani Public School & College, Chittagong commonly referred to as IPSC is a well known private educational institution on Zakir Hossain Road in Chittagong, Bangladesh.  The institution offers primary, secondary and higher secondary education facilities under the Chittagong Education Board.  Founded by Mirza Ahmad Ispahani in 1979 the institution is widely known for its excellent results in S.S.C. and H.S.C. exams and its discipline.

Ispahani Hangar: The Ispahani Hangar is a Pakistan International Airlines wide-body aircraft maintenance hangar at the Jinnah International Airport in Karachi, Pakistan.  It was named in honour of Mirza Ahmad Ispahani, the first and longest serving chairman of Pakistan International Airlines (PIA).  The hangar for wide body and narrow body aircraft with a supporting airframe overhaul shop was completed and commissioned in 1968.

Mirza Ali Behrouze Ispahani: Mirza Ali Behrouze Ispahani was a Bangladeshi businessman from the Ispahani family and the chairman of M. M. Ispahani Limited.

Mirza Ahmad Ashtiani: Mirza Ahmad Ashtiani was born in Tehran.  He was the fourth and youngest son of Mirza Hassan Ashtiani, a prominent jurist under the reign Mozaffar ad-Din Shah Qajar and Naser al-Din Shah Qajar.  He became a jurist and a Shi'a Imam,

Supporting paragraphs: Mirza Ahmad Ispahani Pakistan International Airlines
Answer: Karachi