Qantas is marching towards a mid-year milestone for installing WiFi across its domestic Boeing 737 fleet, with around half of the workhorse jets expected to boast the fast and free Internet service by the end of June.

With some 22 of around 80 Boeing 737s already sporting that tell-tale satellite hump, the airline says the remainder of the fleet is being upgraded "at a rate of approximately one aircraft per week".

Doing the maths shows that as we enter the second half of the year, there'll be a 50:50 chance that your Qantas flight -- at least on routes running the single-aisle Boeing 737s -- will let you stay connected not only above the clouds but on a gate-to-gate basis.

Qantas CEO Alan Joyce says the WiFi rollout is being underwritten by continued bumper results which saw the Flying Kangaroo tuck away a pre-tax profit of US$976 million across the first six months of the 2018 financial year.

(We're awaiting word on when the Qantas WiFi system will be extended to Airbus A330s, as this will certainly be useful on those five-hour transcontinental journeys which can eat up the better part of your working day).

However, once inflight Internet crosses that 50% threshold, something interesting happens from the passenger's perspective: the presence of WiFi moves away from 'surprise and delight' and edges into the realm of a service you expect will be there.

From the passenger's perspective, it goes from an exciting novelty to expected norm -- and ironically, the closer Qantas gets to a "100% WiFi" fleet, the more disappointing it will be for frequent flyers who've come to rely on WiFi but find themselves on a humpless Boeing 737.

(That said, we could be wrong: some travellers may well rejoice to set foot on a flight where they've got a bulletproof reason not to be online.)

It's a bit like the later days of Qantas' Airbus A330 business class upgrade, when most of the A330s sported the new Business Suite but some stragglers were still flying the old 2-2-2 recliners.

However, Qantas is playing a stronger hand than Virgin Australia, which will charge passengers an as-yet-undisclosed fee for a high-speed WiFi connection, although the slower service will remain free.