June 17, 2021

How To Find Cheap Flights Using On The Fly App

How to Find Cheap Flights

One of the most complicated and aggravating things to do is to figure out how to get cheap flight tickets.  If you’re really feeling neurotic, you can combine finding the best time to buy airline tickets and figuring out which airline is the best deal.  We have laid out a step by step guide to finding a cheap airline ticket on your phone without driving yourself crazy.

My preference is to find the best deal I can find, but only when I want to actually buy a ticket.  My approach may not yield the very best deal (if you have a few hours/days to spare, I can suggest a few places to look on the internet where you can wade through hundreds of different opinions on the subject), but it saves time, keeps your sanity, and still gets you the best deal available when you actually have time to focus on the task.

How to Find Cheap Flight Graphic

ITA Google Flight Search App

I know for me, I’m rarely home when I’m trying to buy an airline ticket.  So I need something that is available on my phone.  The best option I’ve found so far is an app called On The Fly which is made by ITA Software and was recently purchased by Google.  On the Fly is available for both the iPhone and android platforms.  For desktop users, the ITA Software has been incorporated into Google Flights.

*Note: the On the Fly app is temporarily not available in the iPhone app store.  The pictures below are from the iPhone version I downloaded previously.  iPhone users can access Google Flights directly on their web browsers.  An app for Google Flights will likely be available in app format soon.

The main reason I rely on this app so much is because it combines a majority of the major airlines (excludes Southwest) and allows for quick searches across airlines, dates, alternative cities and alternative airports.  On top of that, the app doesn’t require you to register and create another username and password just to access the information.

Using the App

I’m going to use an example of flying to Las Vegas from the east coast on a round trip.  I want to make it a weekend trip (2 nights), but I’m open to any weekend over the next month that has the best deal.

On the Fly app intro screen
This is the first screen you see when opening the On the Fly app.

After opening the app, my initial search parameters are going to be leaving from Philadelphia and traveling to Las Vegas and staying for 2 nights.  The search bar gives the option of choosing “specific dates” or choosing “calendar.”  I always use the calendar option because it provides the most flexibility.

Select the departure airport.
The On the Fly app allows you to include flights from nearby airports in your search.
On the Fly app options screen.
The selected search parameters for 2 night round trip flights from Philadelphia to Las Vegas in the month of June.

Search Parameters

After setting those parameters, hit the search button.  The next screen will show a calendar for the month of June.  The bottom of the screen includes a small graph depicting the pricing trends for 2 night, round trip airline tickets during June.

On the Fly flight cost in the 2nd week of june.
Pricing trends for a 2 night round trip flight from Philadelphia to Las Vegas in June.

Search Dates

The first default option chosen by the app is for a flight leaving on Saturday June 11th and returning on June 13th, which happens to be the lowest airfare for a two day ticket for the month of June.

That initial option wouldn’t work for me, since I need to be at work on Monday, so I have the ability to point my finger to a different day of the month to see what the price would be.  In my case, I can only leave on Friday night and return on Sunday, so I point my finger to Friday, June 3rd and the blue box moves to my finger.

On the Fly app flight cost on June 3rd.
Round trip flight cost from Philadelphia to Las Vegas for the weekend of June 3rd.

As you can see from the picture, the Friday night round trip flight on June 3rd and returning on June 5th would cost $343.  By checking the other three Friday night pairs, its very easy to find out that the best deal for a weekend trip to Las Vegas would be to leave Friday June 10th.

On the Fly app flight cost for June 10th.
Round trip flight from Philadelphia to Las Vegas on June 10th.

Prices by Airlines

At this point, I hit “choose flights” while keeping the blue highlight on the June 10th flight date.  On the next screen, I have a choice to make based on my preferences.  If I want the cheapest nonstop flight, I can click Spirit for the $201 flight.  If I’d rather take the cheapest nonstop, non-budget airline (especially if you have status benefits), I can choose American Airlines for the $381 flight.  I could also click the calendar button and go back to the previous screen if I’d like to check the other two weekend dates.

On the Fly app flight costs by airline.
Flight costs arranged by airline for June 10th.

In my case, I’m choosing the American Airlines option because I have status with the airline and would like to earn miles on the flight.  The next screen highlights different departure options and I’ve chosen the 7pm flight.  The last screen highlights return flight options.

On the fly app Philadelphia departure times.
Departure time choices for the American Airlines flight from Philadelphia to Las Vegas.

Flight Decisions

This is when the tough decisions start.  I can choose one of two red eye flights for $381 or I can pay an additional $203 and take a flight that arrives in Philadelphia at 9:50 pm.  If I need to save money, I can choose the red eye, but if I’d rather fly in slightly more comfort, I can choose the more expensive flight.

On the fly app return flights to Philadelphia.
Tough choices on the return flight from Las Vegas to Philadelphia.

I really don’t like flying on red eyes.  So I’m willing to pay the extra money for the non-red eye flight home from Las Vegas.  Although this is not the cheapest flight in absolute terms.  It is the cheapest flight which meets my requirements which include earning miles and not flying on a red eye flight.

On the Fly app flight information screen.
My final decision on the Las Vegas flight.
On the Fly App Miles flown from Philadelphia to Las Vegas.
The On the Fly App shows potential miles flown if you need to plan a mileage run.

The On the Fly app allows you to quickly make decisions about those different scenarios so you can choose the best option for yourself.

The only major downside of the app is that you can not book directly with the airline.  Instead you have the option of either emailing yourself the itinerary, printing it, or saving it within the app.  From there, you can either book directly on the airline web site or call the airline and give them the information from the itinerary.


  • Free.
  • Simple and easy to use.
  • No need to create another user name or password.
  • Ability to quickly compare multiple flight scenarios a month at a time.


  • The On the Fly app has not been updated since Google acquired ITA Software, so there is a risk that Google could discontinue the app in its current form.
  • Does not include all airlines (Southwest Airlines is not included).

For additional resources to save money, see our guide on Comparing Mlife Hotel Discounts to Hyatt.

About First Class Travel Guide 127 Articles
Travel enthusiast that spent years flying in the back of planes and staying at cheaper hotels in order to save a little money. After learning how to leverage airline and hotel loyalty programs, I've developed an interest in luxury travel and write about my experiences with it.

2 Comments on How To Find Cheap Flights Using On The Fly App

  1. This is a fabulous piece of software and sadly what you feared in your article is correct, Google have axed this software, you cannot download it any more and existing users are being cut off from December 2017.

    Aer you aware of any other software that can do the same function as this one, specifically being able to easily see the cost of flights over a month range in a simple graph format.

    OnTheFly you will be missed

    • Unfortunately I’m not aware of anything that gives you that full month view. On the Fly was the best source for flight prices that I’ve found. It’s really a shame they have discontinued it. Google flights is pretty decent, but I haven’t found any good apps that let you use it on your phone. Right now you have to use Google Flights from a desktop; I find it too hard to use from the phone’s native browser. The other app that’s decent is skyscanner. Neither option is a perfect substitute for On the Fly.

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