Comparison

Readback vs Cost Index

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Readback

Streamline your air traffic control note-taking with this utility. Quickly record clearances and updates, eliminating the need for a physical scratchpad. Maintain a comprehensive log of all your flight information for better organization.

Highlights
  • Quickly capture ATC clearances
  • Record ATIS updates
  • Digital log of all clearances
  • Printable flight log
  • Add flight number to log
Features
Read full description

Good morning, Captain! Take your ATC note-taking to the next level. This app allows you to quickly capture ATC clearances, ATIS updates, and more—no more relying on a scratchpad, which isn’t the safest practice. Even the fastest controllers won’t slow you down. Jot down everything with ease and keep a complete log of all your clearances. Whether you’re taxiing at JFK, enroute to Los Angeles, or descending into Heathrow, this app ensures you stay organized and informed. You can even print your log and add your flight number for a full flight record. A must-have tool for every phase of flight.

About

Cost Index

This app helps airline and corporate aircraft operators achieve significant operational savings by calculating the optimum cruise speed for flights based on pilot-inputted conditions and aircraft-specific data. It offers advanced features for cost, fuel, and time optimization, including level change analysis and turbulence margin adjustments.

Highlights
  • Optimum cruise speed calculation
  • Customizable operational data display
  • Minimum fuel burn speed for long range
  • Turbulence margin adjustment
  • Level change analysis for climb/descent decisions
  • Automated data updates
Features
Read full description

Cost Index is an app designed and developed by airline pilots, for airline and corporate aircraft operators. It enables, and has been proven to achieve, significant operational savings. Cruise flight conditions are input by the pilot, then complex algorithms calculate an exact cruise speed which will result in the minimum possible cost for a flight. i.e the optimum cost. Calculations are performed using a tailored aircraft specific data model and customer specific operational costs. Pilots can vary flight level, wind, temperature, weight, and sector cruise distance to find the optimum indicated airspeed and/or mach number. Time difference between optimum cruise speed and minimum time speed can be displayed. Pilots can modify the optimum speed either directly or by decreasing/increasing the time difference. This functionality allows a speed to be selected that will achieve an on-time arrival should this be an overriding factor in the operation. Information displayed on the "Cruise Speed" and "Detail" pages can be customised for the operator. There are over 150 parameters that can be displayed on either of these pages, which can be constructed so that crew do not see any sensitive operational data. As an operational planning/costing tool, all parameters can be made available within the administrator account. For sector lengths approaching the maximum operating range of the aircraft type, a speed for minimum fuel burn is calculated. This speed is better than long range cruise as it takes into account the wind component. When the app detects buffet margin data, a turbulence button is displayed that increases the buffet margin from 1.3g to 1.6g if selected ON. "Level Change" provides unique functionality to aid crew when deciding whether to climb or descend for operational reasons such as turbulence or strong headwinds. There are two features. The first displays the difference in total costs, fuel burn and time, for each flight level when compared to the selected flight level (all other variables the same). The second feature displays the wind required at each level to break even with total cost when compared to the selected level. The flight level with optimum total cost, which is usually the highest achievable level, is highlighted in black with green text. "Downloads" gives the ability to force data updates, although the app will attempt to update it's operational data once it becomes 24 hours old. The number of days since the last update is displayed on the "Downloads" tab badge and also the app icon badge to remind pilots to update the data whilst on the ground. The page has a message area which can display text entered by the administrator. It could be used to promote a flight efficiency programme by giving crews feedback / updates on real savings achieved and tips on new efficient operating techniques. The "Settings" tab is only available to administrator accounts. Its use is for updating operating costs but also includes some customisation functionality. For demonstration purposes, the app has four downloadable sample data sets which contain fictitious data. The following devices are supported: iPad, iPad Retina, iPhone, iPhone Retina 3.5-inch, iPhone Retina 4-inch and iPod Touch. To setup an account for your operational fleet, please contact Flight Efficiency Limited. For more information email: help@flightefficiency.co.uk

Screenshots

Cost Index4 screens

Verdict

The call

The clearest difference is rating: Cost Index at 5.0 against Readback's 2.3. Cost Index also leads on in-app purchases (none vs 5) and device support (3 vs 1). Readback's advantage is update cadence (every 6 months vs every 16 months) and ratings volume (8 vs 1). On price and ads there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Readback sells 5 one-off in-app purchases. Cost Index asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Cost Index holds the better App Store score, 5.0 against 2.3. That said, the two scores are not equally well evidenced: Readback has 8 ratings behind it against 1, so its average is the more settled of the two.

UpkeepUpdate frequency

Readback ships an update every 6 months, Cost Index every 16 months. The most recent releases landed on October 3, 2026 and October 6, 2026 respectively.

Scorecard7 real differences · 3 level
Readback versus Cost Index: the parameters behind the verdict, then further details
ParameterReadbackCost Index
PriceFreeFree
Rating2.3 (8 ratings)5.0 (1 ratings) — better
Positive reviews57.1% of reviews—
Number of ratings8 — better1
Update frequencyEvery 6 months — betterEvery 16 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPadiPhone, iPad, iPod — better
Requires iOS12.08.0 — better
Further details — not scored
Size29 MB3 MB
Age rating4+4+
DeveloperSantiago Borja LopezFlight Efficiency Limited

Customer experience

Readback

All ratings8 ratings
Positive25.0%
Neutral0.0%
Negative75.0%
Written reviews14 reviews
Positive57.1%
Neutral14.3%
Negative28.6%

Cost Index

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

5 purchases

Readback

One-time5
  • Clearance Keypad$0.99
  • Qwerty Keypad$0.99
  • Azerty Keypad$0.99
Show 2 more
  • CDU Keypad$0.99
  • Qwertz Keypad$0.99
None

Cost Index

No in-app purchases

Questions

Is Readback free?
Readback is free to download, with in-app purchases available.
Is Cost Index free?
Cost Index is free to download, with no in-app purchases.
Which has better reviews, Readback or Cost Index?
Cost Index is rated higher. Readback averages 2.3 out of 5 from 8 ratings, while Cost Index averages 5.0 from 1 ratings.
Do Readback or Cost Index have ads?
Neither Readback nor Cost Index shows ads.
Which is updated more often, Readback or Cost Index?
Readback ships an update every 6 months, and Cost Index every 16 months. Most recently, Readback was updated on October 3, 2026 and Cost Index on October 6, 2026.

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