# SkewTLogPro vs Nasapp

The clearest difference is in-app purchases: Nasapp at none against SkewTLogPro's 1. Nasapp also leads on iOS requirement (11.0 vs 17.0). SkewTLogPro's advantage is update cadence (every 2 months vs every 5 months). On price, ads and device support there is nothing between them.

Both are free to download. SkewTLogPro sells 1 in-app purchase, starting at $12.99 per year. Nasapp asks for nothing beyond the download.

SkewTLogPro ships an update every 2 months, Nasapp every 5 months. The most recent releases landed on September 23, 2026 and December 13, 2025 respectively.

## The numbers

| Metric | SkewTLogPro | Nasapp |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[2.7 (97 ratings)](https://appshunter.io/ios/app/skewtlogpro/id522720710/reviews)** | — |
| Number of ratings | **97** | — |
| Positive reviews | 46.7% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 5 months |
| Monetization | Subscription | — |
| Size | 79 MB | 7 MB |
| Requires iOS | 17.0 | **11.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Chad Sandstedt](https://appshunter.io/developer/522720713) | [FUNDACIO PRIVADA CENTRE TECNOLOGIC DE LA QUIMICA DE CATALUNYA](https://appshunter.io/developer/904350549) |

## What reviewers say

### SkewTLogPro

[App page](https://appshunter.io/ios/app/skewtlogpro/id522720710)

Access powerful skew-t log-p charts with one touch. View atmospheric data like temperature, dew point, and winds aloft at various altitudes. Supports current GPS location, airport codes, or lat/lon for detailed weather analysis.

**Highlights:** One-touch skew-t log-p chart access, View charts by GPS, airport ID, or lat/lon, Visual indication of temperature, dew point, winds aloft, Support for International Airport ICAO codes, View charts along your route, Save charts for offline use, Scroll forward/backward for past and forecast charts

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Annual Subscription | $12.99 | per year |

**What reviewers like**

- 📊 Excellent tool for flight planning and weather analysis
- ☁️ Accurate cloud top and bottom predictions
- ❄️ Helpful for identifying icing conditions and freezing levels
- 🎯 Comprehensive atmospheric information in one app
- 👨‍✈️ Essential resource for pilots and weather enthusiasts

**What reviewers complain about**

- 💰 Sudden switch to subscription model for existing paid users
- 🚫 No grandfathering or refunds for previous purchasers
- ⏸️ Extended downtime when data source became unavailable
- 📵 App becomes completely non-functional without subscription
- 💸 High annual subscription fee ($13/year) relative to competitors

**Reported bugs**

- App crashes when selecting locations
- Data timeout errors after updates
- App becomes non-functional when data source API changes
- Slow performance and lag when flipping through hourly forecasts on iPad
- Crashes when manually changing parameters on iPad

**Requested features**

- Interactive charts like rucsoundings with exact value selection
- Extended forecast range beyond 18 hours using GFS data
- Remember last input locations for route planning
- Display CAPE, LFC, EL, and adiabatic lines graphically on chart
- Show weather model being used in the app


### Nasapp

[App page](https://appshunter.io/ios/app/nasapp/id783082260)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is SkewTLogPro free?

SkewTLogPro is free to download, with in-app purchases available.

### Is Nasapp free?

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

### Do SkewTLogPro or Nasapp have ads?

Neither SkewTLogPro nor Nasapp shows ads.

### Which is updated more often, SkewTLogPro or Nasapp?

SkewTLogPro ships an update every 2 months, and Nasapp every 5 months. Most recently, SkewTLogPro was updated on September 23, 2026 and Nasapp on December 13, 2025.

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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.*