Table:
0
A
B
C
D
E
1
Aircraft
Introduced
Retired
Seating
Notes
2
Airbus A319-100
2004
—
156
In service
3
Airbus A320-200
2008
—
180
In service
4
Airbus A321-200
2008
2010
220
Inherited from GB Airways
5
Boeing 737-204
1995
1996
115
Replaced by 737-300s
6
Boeing 737-300
1996
2007
148/9
Replaced by A319s
7
Boeing 737-700
2000
2011
149
Replaced by A319s and A320s

Questions and formulas:
Question: When was the aircraft introduced that could seat 115 people?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,D1="115"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,D2:D7="115"),2))
Level: medium
Question: What year was the aircraft retired when it was replaced by 737-300s?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,E1="replaced by 737-300s"),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,E2:E7="replaced by 737-300s"),3))
Level: medium
Question: What aircraft was introduced in 2004 and has a retired of —?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,(C1="—")*(B1=2004)),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,(C2:C7="—")*(B2:B7=2004)),1))
Level: medium
Question: Which aircraft has 148/9 seating?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,D1="148/9"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,D2:D7="148/9"),1))
Level: medium
Question: How many people can be seated on the aircraft that was introduced in 2008 and has notes of in service?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,(E1="in service")*(B1=2008)),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E7,(E2:E7="in service")*(B2:B7=2008)),4))
Level: medium