Question: When did Qantas aquire the airline it bought to challenge low-cost airline Virgin Blue?

Context paragraphs:
Patrick Corporation: Patrick Corporation Ltd was an Australian publicly listed logistics conglomerate.  Headed by CEO Chris Corrigan before it was absorbed by Toll Holdings in 2006, Patrick had interests in shipping, rail and aviation, including a 62% shareholding in airline Virgin Blue.  Its headquarters were located in Sydney, New South Wales.

V Festival (Australia): The Australian V Festival was an Australian music festival, and a spin-off of the British V Festival.  Like all V Festivals, the event was primarily sponsored by Virgin Mobile.  In Australia the event was also sponsored by airline Virgin Blue.  The V Festival was televised exclusively in Australia by MTV, and from 2008, also by its sister channel VH1.  In 2008 the festival expanded to four shows, with Melbourne and Perth being added.  Since the 2009 V Festival the event has been in hiatus, with the official website stating "V Festival Australia is taking a break at the moment".

Virgin Australia Airlines (NZ): Virgin Australia Airlines (NZ) Limited formerly Pacific Blue Airlines (NZ) Limited, was an airline based in New Zealand.  It was established as the New Zealand subsidiary of Australian airline Virgin Blue (now Virgin Australia).  It was a fully owned subsidiary of Virgin Australia Holdings Limited.  It was renamed Virgin Australia Airlines (NZ) Ltd in December 2011 when its parent company decided to bring all its airlines under the one banner.

Cement Cement: Cement Cement is the second EP by the Australian band Operator Please.  Released in 2007, it is generally regarded as their debut EP, as it was their first commercial release.  It was produced in 2006 by Queensland producer Magoo.  The single "Get What You Want" was one of the 100 most-played songs on Australian radio network Triple J during the year of its release, and has also been used in television ad campaigns for Australian National Youth Week and airline Virgin Blue.

Jetstar Airways: Jetstar Airways Pty Ltd, trading as Jetstar, is an Australian low-cost airline (self-described as "value based") headquartered in Melbourne.  It is a wholly owned subsidiary of Qantas, created in response to the threat posed by low-cost airline Virgin Blue.  Jetstar is part of Qantas' two brand strategy of having Qantas Airways for the premium full-service market and Jetstar for the low-cost market.  Jetstar carries 8.5% of all passengers travelling in and out of Australia.

Jetstar Asia Airways: Jetstar Asia Airways Pte Ltd (operating as Jetstar Asia) is a low-cost airline based in Singapore.  It is one of the Asian offshoots of parent Jetstar Airways, the low-cost subsidiary airline of Australia's Qantas airline.  It operates services to regional destinations in Southeast Asia to countries such as Myanmar, Cambodia, Malaysia, Philippines, Thailand and Vietnam.  It also flies to regional routes in East Asia such as Japan, Taiwan and Hong Kong.  It is the main feeder airline for its parent company Jetstar Airways for budget passengers flying to Australia.  Its sister airlines include Jetstar in New Zealand, Jetstar Pacific and Jetstar Japan.

Impulse Airlines: Impulse Airlines was an independent airline in Australia which operated regional and low cost trunk services between 1992 and 2004.  It was acquired by Qantas in 2001 and later formed the basis of Qantas' low-cost airline Jetstar.  The airline had its head offices on the grounds of Sydney Airport in Mascot.

Virgin Australia: Virgin Australia Airlines Pty Ltd, formerly Virgin Blue Airlines, is Australia's second-largest airline after Qantas and it is the largest airline by fleet size to use the 'Virgin' brand.  Now based in Bowen Hills, Brisbane, the airline was co-founded by British businessman Richard Branson, the founder of parent Virgin Group and former Virgin Blue CEO Brett Godfrey.  It was established in November 1999 with two aircraft operating on a single route, and suddenly found itself catapulted to the position of Australia's second airline after the collapse of Ansett Australia in September 2001.  The airline has grown to directly serve 29 cities in Australia from hubs in Brisbane, Melbourne and Sydney, using a fleet of narrow-body Boeing and Embraer jets; and Airbus and Boeing widebody jets.

Get What You Want: "Get What You Want" is a song by Operator Please and is the second single released in Australia on 27 October 2007 and the third in the United Kingdom on 17 February 2008 from their debut album, "Yes Yes Vindictive".  It debuted at number 40 on the ARIA Singles Chart on 5 November, before later peaking at number 27.  The song was used by airline Virgin Blue airline for its television advertising campaign in 2007.  It also featured as soundtrack in the video games "UEFA Euro 2008" and Test Drive Unlimited 2.

Trans Australia Airlines: Trans Australia Airlines or TAA (renamed Australian Airlines in 1986) was one of the two major Australian domestic airlines between its inception in 1946 and its merger with Qantas in September 1992.  As a result of the "COBRA" (or Common Branding) project, the entire airline was rebranded Qantas about a year later with tickets stating in small print "Australian Airlines Limited trading as Qantas Airways Limited" until the adoption of a single Air Operator Certificate a few years later.  At that point, the entire airline was officially renamed "Qantas Airways Limited" continuing the name and livery of the parent company with the only change being the change of by-line from "The Spirit of Australia" to "The Australian Airline" under the window line with the existing "Qantas" title appearing above.

Supporting paragraphs: Impulse Airlines Jetstar Airways
Answer: 2001