# 737 CSFF vs Plen

The clearest difference is price: Plen at Free against 737 CSFF's $2.99. Plen also leads on update cadence (every 6 days vs every 4 months). On ads, in-app purchases, device support and iOS requirement there is nothing between them.

Plen is free to download; 737 CSFF costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

737 CSFF ships an update every 4 months, Plen every 6 days. The most recent releases landed on October 7, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | 737 CSFF | Plen |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/737-csff/id1551516212/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 6 days** |
| Monetization | Paid | **Free** |
| Size | 11 MB | 203 MB |
| Requires iOS | 17.6 | **17.0** |
| Devices | **iPhone, iPad, Apple Watch** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Dan O'Leary](https://appshunter.io/developer/1177083778) | [Automata Solutions Ltd.](https://appshunter.io/developer/1520244123) |

## What reviewers say

### 737 CSFF

[App page](https://appshunter.io/ios/app/737-csff/id1551516212)

A visual guide to understanding Cold Soaked Fuel Frost (CSFF) on 737 aircraft wings. It references airline handbooks and Boeing FCOM guidance for educational purposes.

**Highlights:** Visual representation of CSFF scenarios, Study guide for 737 wing frost, References North American Airline Flight Handbook, Includes Boeing FCOM guidance, Educational tool for pilots

**In-app purchases:** none


### Plen

[App page](https://appshunter.io/ios/app/plen/id6504163423)

Track aircraft in real-time with live location updates. See planes as they fly and monitor weather conditions along their routes. Discover various types of aircraft with this intuitive radar tool.

**Highlights:** Real-time ADS-B tracking, Live aircraft location updates, Weather updates for flight paths, Discover different types of aircraft, Intuitive radar interface

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is 737 CSFF free?

737 CSFF costs $2.99, with no in-app purchases.

### Is Plen free?

Plen is free to download, with no in-app purchases.

### Do 737 CSFF or Plen have ads?

Neither 737 CSFF nor Plen shows ads.

### Which is updated more often, 737 CSFF or Plen?

737 CSFF ships an update every 4 months, and Plen every 6 days. Most recently, 737 CSFF was updated on October 7, 2026 and Plen on October 3, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*